Q- A cart of mass M₁ = 6 kg is attached to a block of mass M₂ = 3 kg by a string that passes over a friction-less pulley. The system is initially at rest and the table is friction-less. After the block has fallen a distance h = 1 m. What is the work W_s done on the cart by the string?

Solution

Q- A block of mass M = 2.5 kg is released from rest and slides down d = 6 m on an incline that makes an angle  30⁰ with the horizontal. The coefficient of kinetic friction between the block and the incline is m = 0.2.

1. What is the acceleration of the block down the inclined plane?
2. How much work was done on the block by the Earth's gravitational force?
3. How much energy was expended in overcoming the frictional force (thus producing heat, etc.)?
4. What is the kinetic energy of the block?
5. The plane exerts a normal force (perpendicular to its surface) on the block. How much work was done on the block by this normal force?

Solution