Question

If the crate is sliding down the ramp at a constant speed, which forces are unbalanced?

A. the force of gravity along the ramp (1) and the frictional force (3)
B. the weight of the crate against the ramp (2) and the force of the ramp on the crate (4)
C. the force of gravity along the ramp (1) and the weight of the crate against the ramp (2)
D. The crate is not accelerating in any direction, so none of the forces acting on it are unbalanced.

Answer 1

The forces on a crate sliding at constant speed down a ramp are balanced, with gravity along the ramp balanced by friction, and the crate's weight balanced by the normal force from the ramp.

Step-by-step explanation:

If a crate is sliding down a ramp at a constant speed, the forces acting on it must be balanced; otherwise, the crate would accelerate. In the scenario you provided, option D is the correct choice. The force of gravity along the ramp (component of the weight) is balanced by the frictional force, ensuring that the crate does not accelerate. Similarly, the weight of the crate perpendicular to the ramp is balanced by the normal force from the ramp. Since the crate is moving at a constant speed, it is not accelerating, which means the net force in any direction is zero, and thus none of the forces are unbalanced.