A box is initially at rest at the top of a rough slope.
The box slides down the slope.
The weight of the box is 20 N .
The slope is 4.0 m long and 2.0 m high.
The box does 10 J of work against friction as it slides down the slope.
What is the speed of the box as it reaches the bottom of the slope?
A crane on a building site lifts bricks of total mass 200 kg , initially at rest on the ground, with uniform acceleration.
When the bricks are 5.0 m from the ground, they have a speed of .
How much work is done during this process?
2.5 kJ
10.0 kJ
12.5 kJ
A ball of mass 1.2 kg is dropped from a height of 30 m. As it falls, 25% of its initial gravitational potential energy is transferred to thermal energy.
What is the kinetic energy of the ball just before it hits the ground?
27J
90 J
270J
360J