Home
Ask directory
Physics 101 Mechanics
October 2021
23
Physics 101 Mechanics
Q&A Archive of
October 23, 2021
Select Question
October 23 of 2021
What is the gravitational force acting on a 69kg person because another 72kg person is standing 3.4m away? (G = 6.67x10 ^ -11 N. M ^ 2 / kg ^ 2)
An 18-cm-diameter ultracentrifuge produces an extraordinarily large centripetal acceleration of 250,000g, where g is the free-fall acceleration due to gravity. What is its frequency in rpm? What is the apparent weight of a sample with a mass of 0.0030 kg?
A curve on a race track of radius 70 m is banked at a 15° angle. At what speed can a car take this curve without assistance from friction?
Calculate the work that an 85N force does in dragging a block through a distance of 75m, when the force is transmitted by means of a rope at 20 ° with the horizontal.
Kinesiologists—scientists who study human motion—can measure the forces that act on runners as they round a curve. The forces on a runner’s feet are a vertical normal force that, on average, serves to counteract gravity, and a static friction force parallel to the ground and pointing toward the…
The circular blade of a table saw is 25 cm in diameter and spins at 3600 rpm. How much time is required for one revolution? How fast is one of the teeth at the edge of the blade moving? What Is the tooth’s acceleration?
What is a centripetal acceleration (aC) of mercury in its orbit around the sun if its orbit is a circle of radius of 2.4x10^6m? Mass of mercury es 3.30x10^23kg. Mercury takes 88 days to complete one orbit of the sun.
What is the centripetal acceleration (ac) of mercury in its orbit around the sun if its orbit is a circle of radius 2.4 x106 m? The mass of mercury is 3.30 x1023 kg. It takes Mercury 88 days to complete one orbit of the sun.
If the wheels of a car make 73.5 turns in 3.75 seconds and have a diameter of 59 cm, how fast is the car moving?
How fast must a 9,200-g dog run to have a kinetic energy of 180 J?
What will be the angle of incidence of the handle or handle, on a loading cart (see photo), of a force of 40 N to move it 4 feet on a horizontal floor? The work was determined to be 20 J.
If a person removes a 32-kg object from the ocean floor, he does work equivalent to 7.3 kJ, what is the depth of the ocean?
How high would a 50kg mountaineer have to climb to increase his gravitational potential energy by 12.3kJ?
A wind turbine (Figure 10.10) in a wind farm is being shut down for maintenance. It takes 30 s for the turbine to go from its operating angular velocity to a complete stop in which the angular velocity function is ω(t)=[(t-30.0)^2/100.0] rad/s. If the turbine is rotating counterclockwise…
The pressure of a mass of air at 20 °C is halved adiabatically. If the ratio of Cp to Cv for air is 1.41, calculate the resulting temperature.
The fan blades on a turbofan jet engine (shown below) accelerate from rest up to a rotation rate of 40.0 rev/s in 20 s. The increase in angular velocity of the fan is constant in time. (The GE90-110B1 turbofan engine mounted on a Boeing 777, as shown, is currently the largest turbofan engine in…
The fan blades on a turbofan jet engine (shown below) accelerate from rest up to a rotation rate of 40.0 rev/s in 20 s. The increase in angular velocity of the fan is constant in time. (The GE90-110B1 turbofan engine mounted on a Boeing 777, as shown, is currently the largest turbofan engine in…
hi, can help me to solve this question
A plane reaches a velocity of 60 m/s at the end of its runway when taking off. If the runway is 1 kilometer long, what was the plane's acceleration in m/s^2?
You're in a kayak in the Guadalupe River. The river is flowing 8 ft/s (this is probably fast for the Guadalupe in Texas, but we'll ignore that). You see a sandy area on the shore line ahead that you'd like to stop. You start paddling perpendicular to the river current in your kayak to get to…
You're playing a game of cornhole and have been working on your underhand toss. If your toss has an initial velocity of 9 m/s at an angle of 30 degrees with the horizontal - how far does your bag travel before hitting the ground/board?
In a regulation cornhole game the boards are spaced approximately 8.5 meters apart. If you always toss your bag with a 30 degree angle above the horizontal, what initial velocity (in m/s) must you throw with to hit the board (use horizontal distance = 8.5 meters)?
A net horizontal force of 90 N is applied to an object with a mass of 10 kg. What acceleration does the object experience? Report your answer in m/s^2.
A 20 kg object is on a horizontal floor. The coefficient of static friction between the floor and the object is 0.30. What frictional force (in Newtons) must you overcome to slide the object on the floor?
You need to supply a 260 Newton force to slide a 70 Newton object at a constant speed. What is the coefficient of kinetic friction between the object and the ground?
Suppose you wish to accelerate a 20,000-Newton truck from 10 m/s to 40 m/s in a total time of 10 seconds. What force (in Newtons) is required to do this?
What is the momentum of a 80 kg runner at 4.5 m/s? Report your answer in kg*m/s.
A 400 kg vehicle traveling 8 m/s comes to a stop. What was the impulse needed to stop this vehicle? Report your answer as a positive number and in kg*m/s.
A 1500 kg car traveling east at 8 m/s collides head-on with a 1900 kg SUV traveling west at 2 m/s. The road is very icy (assume no friction during collision). If the collision is inelastic, what is the new velocity (in m/s) of the vehicles after the collision? Take east as the positive…
Ball 1 of mass 1.5 kg is traveling towards Ball 2 of mass 1.1 kg. Ball 2 is initially at rest. The balls collide elastically. After the collision, Ball 1 has a velocity of 0.545 m/s and Ball 2 has a velocity of 4.03 m/s (they are both traveling in the same direction after the collision).…
For the linear harmonic diatomic chain, find the amplitude ratios u/v for the two branches at kmax = ?/a. Show that at this value of k the two lattices act as if they were decoupled: one lattice remains at rest while the other lattice moves
A racetrack has the shape of an inverted cone, as the drawing shows. On this surface the cars race in circles that are parallel to the ground. For a speed of 43.7 m/s, at what value of the distance d should a driver locate his car if he wishes to stay on a circular path without depending on…
A block of mass M, supported by a string, rest on and incline making and angle of O with the horizontal (Fig 2). The length of the string is L and its mass is????? ? ????. Derive an expression for the time it takes a transverse wave to travel from one end of the string to the others.
As shown in figure 1, water is pumped into a tall vertical cylinder at a volume flow rate R. Theradius of the cylinder is r, and at the open top of the cylinder a tuning fork vibrates with a frequency f. As the water rises, how much time elapses between successive resonances.
On a banked race track, the smallest circular path on which cars can move has a radius of 107 m, while the largest has a radius of 150 m, as the drawing illustrates. The height of the outer wall is 17.6 m. Find (a) the smallest and (b) the largest speed at which cars can move on this track…
A car is safely negotiating an unbanked circular turn at a speed of 27 m/s. The road is dry, and the maximum static frictional force acts on the tires. Suddenly a long wet patch in the road decreases the maximum static frictional force to one third of its dry-road value. If the car is to…
QUESTION 2 [8 marks] A shell is fired from level ground with an initial velocity of 71 m/s at an angle 55.9° above the horizontal. Assume negligible air resistance. (a) Find the horizontal and vertical components of the shell’s initial velocity. [2] (b) How long…
For background pertinent to this problem, review Conceptual Example 6. In Figure 5.7 the man hanging upside down is holding a partner who weighs 510 N. Assume that the partner moves on a circle that has a radius of 4.81 m. At a swinging speed of 5.05 m/s, what force must the man apply to his…
Self-practice - A smooth \( 2-\mathrm{kg} \) collar \( C \), fits loosely on the vertical shaft. If the spring is unstretched when the collar is in the position \( A \), determine the speed at which the collar is moving when \( y=1 \mathrm{~m} \) if it is released from rest at \( A \).
Why do the electrostatic field lines not form closed loops? (
Two thin lenses of power + 4D and – 2D are in contact. What is the focal length of the combination?
Why is photoelectric emission not possible at all frequencies?
State de-Broglie hypothesis.
What is the ratio of radii of the orbits corresponding to first excited state and ground state in a hydrogen atom?
What is mass in 6.77mol of H20
A moving electron has kinetic energy, K1. After a net amount of work W has been done on it, the electron is moving one quarter as fast as in the opposite direction.(a) Find W in terms of K1.(b) Does your answer depend on the final direction of the electron’s motion?
A car is stopped in a distance D by a constant friction force that is independent of the car’s speed. What is the stopping distance (in terms of D)(a) if the car’s initial speed is tripled, and(b) if the speed is the same as it originally was but the friction force is tripled? (Solve using the…
Distinguish between ‘point-to-point’ and ‘broadcast’ modes of communication
In half-wave rectification, what is the output frequency if the input frequency is 50 Hz. What is the output frequency of a full-wave rectifier for the same input frequency.
17. When a forward bias is applied to a p-n junction, it (a) raises the potential barrier. (b) reduces the majority carrier current to zero. (c) lowers the potential barrier. (d) None of the above.
10.What do you mean by hole in a circuit? Write its two characteristics?
What are the advantages and disadvantages of semiconductor devices over vacuum tubes?
6.A transistor has a current gain of 30. If the collector resistance is 6k, input resistance is 1k, calculate its voltage gain?
5.What do you mean by depletion region and potential barrier in junction diode?
what happens when washing soda is heated.
A painter climbs a ladder that is 2.75 m long leaning against a vertical wall. The ladder makes an angle with the wall which is 30.0°. The mass of the painter is 75.0kg.(a) How much work does gravity do on the painter?(b) Does your answer in part (a) depend on whether the painter climbs at…
You push a 3.9 kg block against a horizontal spring, compressing the spring by 26 cm. Then you release the block, and the spring sends it sliding across a tabletop. It stops 77 cm from where you released it. The spring constant is 200 N/m. What is the coefficient of kinetic friction between the…
A painter climbs a ladder that is 2.75 m long leaning against a vertical wall. The ladder makes an angle with the wall which is 30.0°. The mass of the painter is 75.0kg.(a) How much work does gravity do on the painter?(b) Does your answer in part (a) depend on whether the painter climbs at…
In the figure, a chain is held on a frictionless table with 1/ 5 of its length hanging over the edge. If the chain has length L = 34 cm and mass m = 29 g, how much work is required to pull the hanging part back onto the table?
Tarzan, who weighs 684 N, swings from a cliff at the end of a convenient vine that is 17 m long (see the figure). From the top of the cliff to the bottom of the swing, he descends by 4.9 m. The vine will break if the force on it exceeds 1630 N. What would the greatest force on the vine be…
A block of mass m = 1.70 kg is dropped from height h = 35.0 cm onto a spring of spring constant k = 2180 N/m (see the figure). Find the maximum distance the spring is compressed.
What is the gravitational force acting on a 69kg person because another 72kg person is standing 3.4m away? (G = 6.67x10 ^ -11 N. M ^ 2 / kg ^ 2)
An 18-cm-diameter ultracentrifuge produces an extraordinarily large centripetal acceleration of 250,000g, where g is the free-fall acceleration due to gravity. What is its frequency in rpm? What is the apparent weight of a sample with a mass of 0.0030 kg?
A curve on a race track of radius 70 m is banked at a 15° angle. At what speed can a car take this curve without assistance from friction?
Calculate the work that an 85N force does in dragging a block through a distance of 75m, when the force is transmitted by means of a rope at 20 ° with the horizontal.
Kinesiologists—scientists who study human motion—can measure the forces that act on runners as they round a curve. The forces on a runner’s feet are a vertical normal force that, on average, serves to counteract gravity, and a static friction force parallel to the ground and pointing toward the…
The circular blade of a table saw is 25 cm in diameter and spins at 3600 rpm. How much time is required for one revolution? How fast is one of the teeth at the edge of the blade moving? What Is the tooth’s acceleration?
What is a centripetal acceleration (aC) of mercury in its orbit around the sun if its orbit is a circle of radius of 2.4x10^6m? Mass of mercury es 3.30x10^23kg. Mercury takes 88 days to complete one orbit of the sun.
What is the centripetal acceleration (ac) of mercury in its orbit around the sun if its orbit is a circle of radius 2.4 x106 m? The mass of mercury is 3.30 x1023 kg. It takes Mercury 88 days to complete one orbit of the sun.
If the wheels of a car make 73.5 turns in 3.75 seconds and have a diameter of 59 cm, how fast is the car moving?
How fast must a 9,200-g dog run to have a kinetic energy of 180 J?
What will be the angle of incidence of the handle or handle, on a loading cart (see photo), of a force of 40 N to move it 4 feet on a horizontal floor? The work was determined to be 20 J.
If a person removes a 32-kg object from the ocean floor, he does work equivalent to 7.3 kJ, what is the depth of the ocean?
How high would a 50kg mountaineer have to climb to increase his gravitational potential energy by 12.3kJ?
A wind turbine (Figure 10.10) in a wind farm is being shut down for maintenance. It takes 30 s for the turbine to go from its operating angular velocity to a complete stop in which the angular velocity function is ω(t)=[(t-30.0)^2/100.0] rad/s. If the turbine is rotating counterclockwise…
The pressure of a mass of air at 20 °C is halved adiabatically. If the ratio of Cp to Cv for air is 1.41, calculate the resulting temperature.
The fan blades on a turbofan jet engine (shown below) accelerate from rest up to a rotation rate of 40.0 rev/s in 20 s. The increase in angular velocity of the fan is constant in time. (The GE90-110B1 turbofan engine mounted on a Boeing 777, as shown, is currently the largest turbofan engine in…
The fan blades on a turbofan jet engine (shown below) accelerate from rest up to a rotation rate of 40.0 rev/s in 20 s. The increase in angular velocity of the fan is constant in time. (The GE90-110B1 turbofan engine mounted on a Boeing 777, as shown, is currently the largest turbofan engine in…
hi, can help me to solve this question
A plane reaches a velocity of 60 m/s at the end of its runway when taking off. If the runway is 1 kilometer long, what was the plane's acceleration in m/s^2?
You're in a kayak in the Guadalupe River. The river is flowing 8 ft/s (this is probably fast for the Guadalupe in Texas, but we'll ignore that). You see a sandy area on the shore line ahead that you'd like to stop. You start paddling perpendicular to the river current in your kayak to get to…
You're playing a game of cornhole and have been working on your underhand toss. If your toss has an initial velocity of 9 m/s at an angle of 30 degrees with the horizontal - how far does your bag travel before hitting the ground/board?
In a regulation cornhole game the boards are spaced approximately 8.5 meters apart. If you always toss your bag with a 30 degree angle above the horizontal, what initial velocity (in m/s) must you throw with to hit the board (use horizontal distance = 8.5 meters)?
A net horizontal force of 90 N is applied to an object with a mass of 10 kg. What acceleration does the object experience? Report your answer in m/s^2.
A 20 kg object is on a horizontal floor. The coefficient of static friction between the floor and the object is 0.30. What frictional force (in Newtons) must you overcome to slide the object on the floor?
You need to supply a 260 Newton force to slide a 70 Newton object at a constant speed. What is the coefficient of kinetic friction between the object and the ground?
Suppose you wish to accelerate a 20,000-Newton truck from 10 m/s to 40 m/s in a total time of 10 seconds. What force (in Newtons) is required to do this?
What is the momentum of a 80 kg runner at 4.5 m/s? Report your answer in kg*m/s.
A 400 kg vehicle traveling 8 m/s comes to a stop. What was the impulse needed to stop this vehicle? Report your answer as a positive number and in kg*m/s.
A 1500 kg car traveling east at 8 m/s collides head-on with a 1900 kg SUV traveling west at 2 m/s. The road is very icy (assume no friction during collision). If the collision is inelastic, what is the new velocity (in m/s) of the vehicles after the collision? Take east as the positive…
Ball 1 of mass 1.5 kg is traveling towards Ball 2 of mass 1.1 kg. Ball 2 is initially at rest. The balls collide elastically. After the collision, Ball 1 has a velocity of 0.545 m/s and Ball 2 has a velocity of 4.03 m/s (they are both traveling in the same direction after the collision).…
For the linear harmonic diatomic chain, find the amplitude ratios u/v for the two branches at kmax = ?/a. Show that at this value of k the two lattices act as if they were decoupled: one lattice remains at rest while the other lattice moves
A racetrack has the shape of an inverted cone, as the drawing shows. On this surface the cars race in circles that are parallel to the ground. For a speed of 43.7 m/s, at what value of the distance d should a driver locate his car if he wishes to stay on a circular path without depending on…
A block of mass M, supported by a string, rest on and incline making and angle of O with the horizontal (Fig 2). The length of the string is L and its mass is????? ? ????. Derive an expression for the time it takes a transverse wave to travel from one end of the string to the others.
As shown in figure 1, water is pumped into a tall vertical cylinder at a volume flow rate R. Theradius of the cylinder is r, and at the open top of the cylinder a tuning fork vibrates with a frequency f. As the water rises, how much time elapses between successive resonances.
On a banked race track, the smallest circular path on which cars can move has a radius of 107 m, while the largest has a radius of 150 m, as the drawing illustrates. The height of the outer wall is 17.6 m. Find (a) the smallest and (b) the largest speed at which cars can move on this track…
A car is safely negotiating an unbanked circular turn at a speed of 27 m/s. The road is dry, and the maximum static frictional force acts on the tires. Suddenly a long wet patch in the road decreases the maximum static frictional force to one third of its dry-road value. If the car is to…
QUESTION 2 [8 marks] A shell is fired from level ground with an initial velocity of 71 m/s at an angle 55.9° above the horizontal. Assume negligible air resistance. (a) Find the horizontal and vertical components of the shell’s initial velocity. [2] (b) How long…
For background pertinent to this problem, review Conceptual Example 6. In Figure 5.7 the man hanging upside down is holding a partner who weighs 510 N. Assume that the partner moves on a circle that has a radius of 4.81 m. At a swinging speed of 5.05 m/s, what force must the man apply to his…
Self-practice - A smooth \( 2-\mathrm{kg} \) collar \( C \), fits loosely on the vertical shaft. If the spring is unstretched when the collar is in the position \( A \), determine the speed at which the collar is moving when \( y=1 \mathrm{~m} \) if it is released from rest at \( A \).
Why do the electrostatic field lines not form closed loops? (
Two thin lenses of power + 4D and – 2D are in contact. What is the focal length of the combination?
Why is photoelectric emission not possible at all frequencies?
State de-Broglie hypothesis.
What is the ratio of radii of the orbits corresponding to first excited state and ground state in a hydrogen atom?
What is mass in 6.77mol of H20
A moving electron has kinetic energy, K1. After a net amount of work W has been done on it, the electron is moving one quarter as fast as in the opposite direction.(a) Find W in terms of K1.(b) Does your answer depend on the final direction of the electron’s motion?
Distinguish between ‘point-to-point’ and ‘broadcast’ modes of communication
In half-wave rectification, what is the output frequency if the input frequency is 50 Hz. What is the output frequency of a full-wave rectifier for the same input frequency.
17. When a forward bias is applied to a p-n junction, it (a) raises the potential barrier. (b) reduces the majority carrier current to zero. (c) lowers the potential barrier. (d) None of the above.
10.What do you mean by hole in a circuit? Write its two characteristics?
What are the advantages and disadvantages of semiconductor devices over vacuum tubes?
6.A transistor has a current gain of 30. If the collector resistance is 6k, input resistance is 1k, calculate its voltage gain?
5.What do you mean by depletion region and potential barrier in junction diode?
what happens when washing soda is heated.
A painter climbs a ladder that is 2.75 m long leaning against a vertical wall. The ladder makes an angle with the wall which is 30.0°. The mass of the painter is 75.0kg.(a) How much work does gravity do on the painter?(b) Does your answer in part (a) depend on whether the painter climbs at…
You push a 3.9 kg block against a horizontal spring, compressing the spring by 26 cm. Then you release the block, and the spring sends it sliding across a tabletop. It stops 77 cm from where you released it. The spring constant is 200 N/m. What is the coefficient of kinetic friction between the…
A painter climbs a ladder that is 2.75 m long leaning against a vertical wall. The ladder makes an angle with the wall which is 30.0°. The mass of the painter is 75.0kg.(a) How much work does gravity do on the painter?(b) Does your answer in part (a) depend on whether the painter climbs at…
In the figure, a chain is held on a frictionless table with 1/ 5 of its length hanging over the edge. If the chain has length L = 34 cm and mass m = 29 g, how much work is required to pull the hanging part back onto the table?
Tarzan, who weighs 684 N, swings from a cliff at the end of a convenient vine that is 17 m long (see the figure). From the top of the cliff to the bottom of the swing, he descends by 4.9 m. The vine will break if the force on it exceeds 1630 N. What would the greatest force on the vine be…
A block of mass m = 1.70 kg is dropped from height h = 35.0 cm onto a spring of spring constant k = 2180 N/m (see the figure). Find the maximum distance the spring is compressed.