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November 2021
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Physics 101 Mechanics
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November 2, 2021
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November 2 of 2021
A person observes that the amount of time between adjacent pulses in a sound wave is 0.500 seconds. What is the wave frequency? What is the wavelength of this wave?
A hydrogen atom has its electron in the n=5 level. What is the momentum, mv, of the electron in its orbit
For spherically symmetrical potentials, we can apply the WKB approximation to the radial equation, $-frac{hbar^2}{2m}frac{d^2u}{dr^2} + left[V + frac{hbar^2}{2m}frac{l(l+1)}{r^2} ight]u = Eu$ In the case l = 0, it is reasonable to use the equation $int_{0}^{r_0} p(r)dr = (n - 1/4)pihbar$ where…
This was asked as part of the 'Module 4 Dimensional Analysis' of a fluid mechanics course. I would appreciate assistance in understanding how to how about solving this question. I would appreciate it if you explained each step you did. I believe that the 'Dimensional Analysis' section of the…
A bulldozer drags a log weighing 500 N along a rough surface. The cable attached to the log makes an angle of 30° with the ground. The coefficient of static friction between the log and the ground is 0.5. What is the minimum amount of tension needed in the cable in order to move the log?
A small ball is kicked at the ground with an initial speed of 25 m/s at an angle ?. The ball reaches the maximum height of 63.8 m above the ground. a) How long does the ball reach the maximum height above the ground? b) How far does the ball travel horizontally before returning to the…
A motorbike moves along a straight road through a distance of 1.8 km. Through the first 2/3 of that distance, it accelerates from rest at a rate of 1.5 m/s2 . Through the rest of that distance, it decelerates to rest at rate of 0.5 m/s2 . a) What is its travel time through the distance? b)…
Can You help me with this please?
A beam of 650 nm light is directed upon two thin slits that are separated by a distance of 0.750 mm. A screen is placed 1.50 m away to capture the interference pattern. What is the distance from the 1st order maxima to 3rd order minima?
A spring with spring constant k = 125 N/m is used to pull a 25 N wooden block horizontally across a tabletop. The coefficient of friction between the block and the table is µ k = 0.20. By how much does this spring stretch from its equilibrium length?
A beam of 650 nm light is directed upon two thin slits that are separated by a distance of 0.750 mm. At what angle in degrees does the 3rd order minima occur as measured relative to the principle axis? Only enter a number rounded to 3 decimal places.
A 20 cm long spring is attached to a wall. When pulled horizontally with a force of 100 N, the spring stretches to a length of 22 cm. What is the value of the spring constant? The same spring is now used in a tug of war. Two people pull on the ends, each with a force of 100 N. How long is…
The same spring is now suspended from a hook and a 10.2 kg block is attached to the bottom end. How long is the stretched spring?
A 20 cm long spring is attached to a wall. When pulled horizontally with a force of 100 N, the spring stretches to a length of 22 cm. What is the value of the spring constant?
Why can’t you stand on tiptoes if your toes are against a wall? Stated otherwise, what are the requirements for balance?
A 2 m long board weighing 50 N extends out over the edge of a table, with 40% of the board’s length off the table. How far beyond the table edge can a 25 N cat walk before the board begins to tilt?
Can I get help with this please?
A baseball bat has a mass of 0.82 kg and is 0.86 m long. It’s held vertically and then allowed to fall. What is the bat’s angular acceleration when it has reached 20° from the vertical? (Model the bat as a uniform cylinder).
The motor in a CD player exerts a torque of 7.0 x 10-4 N · m. What is the disk’s angular acceleration? (A CD has a diameter of 12.0 cm and a mass of 16 g.)
Can I get help with this one please?
Revolutionaries attempt to pull down a statue of the Great Leader by pulling on a rope tied to the top of his head. The statue is 17 m tall, and they pull with a force of 4200 N at an angle of 65° to the horizontal. What is the torque they exert on the statue? If they are standing to the…
A high-speed drill rotating CCW takes 2.5 s to speed up to 2400 rpm. What is the drill’s angular acceleration? How many revolutions does it make as it reaches top speed?
The Globe of Death is a spherical cage in which motorcyclists ride in circular paths at high speeds. One outfit claims that riders achieve a speed of 60 mph in a 16 ft diameter sphere. What would be the period for this motion? What would be the apparent weight of a 60 kg rider at the…
At Talladega, a NASCAR track, the turns have a 370 m radius and are banked at 33°. At what speed can a car go around this corner with no assistance from friction?
Phobos is the closer of Mars’ two small moons, orbiting at 9400 km from the center of Mars, a planet of mass 6.4 × 10^23 kg. What is Phobos’ orbital period? How does this compare to the length of the Martian day, which is just shy of 25 hours?
A spacecraft is orbiting the moon in an orbit very close to the surface—possible because of the moon’s lack of atmosphere. What is the craft’s speed? The period of its orbit?
What is the magnitude and direction of the force of gravity on a 60 kg person?
A typical bowling ball is spherical, weighs 16 pounds, and has a diameter of 8.5 in. Suppose two bowling balls are right next to each other in the rack. What is the gravitational force between the two—magnitude and direction? What is the magnitude and direction of the force of gravity on a…
Phobos is one of two small moons that orbit Mars. Phobos is a very small moon, and has correspondingly small gravity— it varies, but a typical value is about 6 mm/s2. Phobos isn’t quite round, but it has an average radius of about 11 km. What would be the orbital speed around Phobos, …
A handful of professional skaters have taken a skateboard through an inverted loop in a full pipe. For a typical pipe with diameter 14 ft, what is the minimum speed the skater must have at the very top of the loop?
A roller coaster car goes through a vertical loop at a constant speed. For positions A to E, rank order the: centripetal acceleration normal force apparent weight
A car of mass 1500 kg goes over a hill at a speed of 20 m/s. The shape of the hill is approximately circular, with a radius of 60 m, as in the figure at right. When the car is at the highest point of the hill, What is the force of gravity on the car? What is the normal force of the…
A world-class thrower can get the hammer up to a speed of 29 m/s. If an athlete swings the mass in a horizontal circle centered on the handle he uses to hold the chain, what is the tension in the chain?
A level curve on a country road has a radius of 150 m. What is the maximum speed at which this curve can be safely negotiated on a rainy day when the coefficient of friction between the tires on a car and the road is 0.40?
The hard drive disk in the earlier example rotates at 7200 rpm. The disk has a diameter of 5.1 in (13 cm). What is the speed of a point 6.0 cm from the center axle? What is the acceleration of this point on the disk?
The shaft of an elevator motor turns clockwise at 180 rpm for 10 s, is at rest for 15 s, then turns counterclockwise at 240 rpm for 12.5 s. What is the angular displacement of the shaft during this motion? Draw angular position and angular velocity graphs for the shaft’s motion.
The ratio of the diameters of the small piston to the large piston of a hydraulic lift is 1:10. Find (a) the ratio of the force on the small piston to the force on the large piston and (b) the ration of the pressure on the small piston to the pressure on the big piston.
A person observes that the amount of time between adjacent pulses in a sound wave is 0.500 seconds. What is the wave frequency? What is the wavelength of this wave?
A hydrogen atom has its electron in the n=5 level. What is the momentum, mv, of the electron in its orbit
For spherically symmetrical potentials, we can apply the WKB approximation to the radial equation, $-frac{hbar^2}{2m}frac{d^2u}{dr^2} + left[V + frac{hbar^2}{2m}frac{l(l+1)}{r^2} ight]u = Eu$ In the case l = 0, it is reasonable to use the equation $int_{0}^{r_0} p(r)dr = (n - 1/4)pihbar$ where…
This was asked as part of the 'Module 4 Dimensional Analysis' of a fluid mechanics course. I would appreciate assistance in understanding how to how about solving this question. I would appreciate it if you explained each step you did. I believe that the 'Dimensional Analysis' section of the…
A bulldozer drags a log weighing 500 N along a rough surface. The cable attached to the log makes an angle of 30° with the ground. The coefficient of static friction between the log and the ground is 0.5. What is the minimum amount of tension needed in the cable in order to move the log?
A small ball is kicked at the ground with an initial speed of 25 m/s at an angle ?. The ball reaches the maximum height of 63.8 m above the ground. a) How long does the ball reach the maximum height above the ground? b) How far does the ball travel horizontally before returning to the…
A motorbike moves along a straight road through a distance of 1.8 km. Through the first 2/3 of that distance, it accelerates from rest at a rate of 1.5 m/s2 . Through the rest of that distance, it decelerates to rest at rate of 0.5 m/s2 . a) What is its travel time through the distance? b)…
Can You help me with this please?
A beam of 650 nm light is directed upon two thin slits that are separated by a distance of 0.750 mm. A screen is placed 1.50 m away to capture the interference pattern. What is the distance from the 1st order maxima to 3rd order minima?
A spring with spring constant k = 125 N/m is used to pull a 25 N wooden block horizontally across a tabletop. The coefficient of friction between the block and the table is µ k = 0.20. By how much does this spring stretch from its equilibrium length?
A beam of 650 nm light is directed upon two thin slits that are separated by a distance of 0.750 mm. At what angle in degrees does the 3rd order minima occur as measured relative to the principle axis? Only enter a number rounded to 3 decimal places.
A 20 cm long spring is attached to a wall. When pulled horizontally with a force of 100 N, the spring stretches to a length of 22 cm. What is the value of the spring constant? The same spring is now used in a tug of war. Two people pull on the ends, each with a force of 100 N. How long is…
The same spring is now suspended from a hook and a 10.2 kg block is attached to the bottom end. How long is the stretched spring?
A 20 cm long spring is attached to a wall. When pulled horizontally with a force of 100 N, the spring stretches to a length of 22 cm. What is the value of the spring constant?
Why can’t you stand on tiptoes if your toes are against a wall? Stated otherwise, what are the requirements for balance?
A 2 m long board weighing 50 N extends out over the edge of a table, with 40% of the board’s length off the table. How far beyond the table edge can a 25 N cat walk before the board begins to tilt?
Can I get help with this please?
A baseball bat has a mass of 0.82 kg and is 0.86 m long. It’s held vertically and then allowed to fall. What is the bat’s angular acceleration when it has reached 20° from the vertical? (Model the bat as a uniform cylinder).
The motor in a CD player exerts a torque of 7.0 x 10-4 N · m. What is the disk’s angular acceleration? (A CD has a diameter of 12.0 cm and a mass of 16 g.)
Can I get help with this one please?
Revolutionaries attempt to pull down a statue of the Great Leader by pulling on a rope tied to the top of his head. The statue is 17 m tall, and they pull with a force of 4200 N at an angle of 65° to the horizontal. What is the torque they exert on the statue? If they are standing to the…
A high-speed drill rotating CCW takes 2.5 s to speed up to 2400 rpm. What is the drill’s angular acceleration? How many revolutions does it make as it reaches top speed?
The Globe of Death is a spherical cage in which motorcyclists ride in circular paths at high speeds. One outfit claims that riders achieve a speed of 60 mph in a 16 ft diameter sphere. What would be the period for this motion? What would be the apparent weight of a 60 kg rider at the…
At Talladega, a NASCAR track, the turns have a 370 m radius and are banked at 33°. At what speed can a car go around this corner with no assistance from friction?
Phobos is the closer of Mars’ two small moons, orbiting at 9400 km from the center of Mars, a planet of mass 6.4 × 10^23 kg. What is Phobos’ orbital period? How does this compare to the length of the Martian day, which is just shy of 25 hours?
A spacecraft is orbiting the moon in an orbit very close to the surface—possible because of the moon’s lack of atmosphere. What is the craft’s speed? The period of its orbit?
What is the magnitude and direction of the force of gravity on a 60 kg person?
A typical bowling ball is spherical, weighs 16 pounds, and has a diameter of 8.5 in. Suppose two bowling balls are right next to each other in the rack. What is the gravitational force between the two—magnitude and direction? What is the magnitude and direction of the force of gravity on a…
Phobos is one of two small moons that orbit Mars. Phobos is a very small moon, and has correspondingly small gravity— it varies, but a typical value is about 6 mm/s2. Phobos isn’t quite round, but it has an average radius of about 11 km. What would be the orbital speed around Phobos, …
A handful of professional skaters have taken a skateboard through an inverted loop in a full pipe. For a typical pipe with diameter 14 ft, what is the minimum speed the skater must have at the very top of the loop?
A roller coaster car goes through a vertical loop at a constant speed. For positions A to E, rank order the: centripetal acceleration normal force apparent weight
A car of mass 1500 kg goes over a hill at a speed of 20 m/s. The shape of the hill is approximately circular, with a radius of 60 m, as in the figure at right. When the car is at the highest point of the hill, What is the force of gravity on the car? What is the normal force of the…
A world-class thrower can get the hammer up to a speed of 29 m/s. If an athlete swings the mass in a horizontal circle centered on the handle he uses to hold the chain, what is the tension in the chain?
A level curve on a country road has a radius of 150 m. What is the maximum speed at which this curve can be safely negotiated on a rainy day when the coefficient of friction between the tires on a car and the road is 0.40?
The hard drive disk in the earlier example rotates at 7200 rpm. The disk has a diameter of 5.1 in (13 cm). What is the speed of a point 6.0 cm from the center axle? What is the acceleration of this point on the disk?
The shaft of an elevator motor turns clockwise at 180 rpm for 10 s, is at rest for 15 s, then turns counterclockwise at 240 rpm for 12.5 s. What is the angular displacement of the shaft during this motion? Draw angular position and angular velocity graphs for the shaft’s motion.
The ratio of the diameters of the small piston to the large piston of a hydraulic lift is 1:10. Find (a) the ratio of the force on the small piston to the force on the large piston and (b) the ration of the pressure on the small piston to the pressure on the big piston.