A 68 kg crate is dragged across a floor by pulling on a rope...

Name: Problem 11, Chapter 6: Principles of Physics
Uploaded: 2022-03-15T00:21:37-08:00
Duration: 6 min 18 s
Channel: Sandeep Kumar Dhania
Description: A 68 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 15° above the horizontal. (a) If the coefficient of static friction is 0.65, what minimum force magnitude is required from the rope to start the crate moving? (b) If mk 0.35, what is the magnitude of the initial acceleration of the crate?

A 68 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 15° above the horizontal. (a) If the coefficient of static friction is 0.65, what minimum force magnitude is required from the rope to start the crate moving? (b) If mk 0.35, what is the magnitude of the initial acceleration of the crate?

A 68 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 15° above the horizontal. (a) If the
coefficient of static friction is 0.65, what minimum force magnitude
is required from the rope to start the crate moving? (b) If mk
0.35, what is the magnitude of the initial acceleration of the crate?

Key Concepts

Newton’s Second Law and Net Force

Newton’s second law states that the net force acting on an object equals the product of its mass and acceleration (F_net = ma). This law is applied after determining all the individual forces acting on the object through a free body diagram. By summing these forces in the horizontal direction, one can determine the net force and thus calculate the required acceleration or the minimum force necessary to start or maintain motion.

Free Body Diagram

A free body diagram is a graphical illustration used to visualize all the forces acting on an object. It helps in identifying the gravitational force, normal force, frictional force, and the applied forces (with their respective components) which simplifies the application of Newton’s laws to determine the conditions for motion.

Kinetic Friction

Kinetic friction is the resistive force acting on an object in motion, typically described by a coefficient of kinetic friction (?k) which is usually lower than the static friction coefficient. It comes into play once an object has begun moving, influencing the net force acting on the object and thereby its acceleration.

Static Friction

Static friction is the force that resists the initiation of sliding motion between two contacting surfaces. It is characterized by a coefficient (?s) that describes how much frictional force can be generated before the object starts moving. In problems involving an object at rest being acted on by an external force, determining the minimum force required to overcome static friction is essential for initiating motion.

Force Decomposition

Force decomposition involves breaking a force applied at an angle into its horizontal and vertical components. This is crucial in many physics problems because it allows the separate analysis of forces acting in different directions, especially in situations where one component of the force reduces the effective weight and thus the normal force, which in turn affects friction.

Transcript

Please give Ace some feedback