Question

PHYS 123:: Physics Illinois :: University of Illinois at Urbana-Champaign Imagine you are in the lab rolling balls down the ramp and measuring their speed at the bottom Homew 1) Suppose you roll the same ball twice starting at the same height above the ground. In the first case the ramp is long and has a gentle slope, and in the second case the ramp is short and steep. In which case does it take the ball the longest time to reach the bottom of the ramp? The ball takes longer to get to the end of the short ramp The ball takes the same time to get to the bottom of both ramps The ball takes longer to get to the end of the long ramp Submit 2) Suppose you are using a lever to lift a box that has a weight of 1000 lbs. You put one end of the lever under the box and push down on the other end. You place the fulcrum at the position that allows you to lift the box off the ground by pushing down on the other end of the lever with a force of 50 lbs. Is the fulcrum closer to the end of the lever under the box or closer to the other end? Closer to the end under the box Closer to the other end. The fulcrum is in the middle of the lever. Submit 3) If you push the other end of the lever down 20 inches. How far does the box rise? 1 inch 2 inches 10 inches Submit 4) Suppose you moved the fulcrum a bit closer to the end of the lever under the box. How much force will you need to push with at the other end in order to lift the box? More than 50 lbs Less than 50 lbs Still 50 lbs

Answer 1

1) The velocity will be same at the end for both ramps. However, a steeper ramp will cause the ball to reach higher speed in shorter time.

2) Close to the end under the box. Remember, the closer the fulcrum is to the end under the load, the less effort we need to put

3) Not sure about this one. May be you are correct

4) As we have moved closer to end under load, we will need less than 50 lbs.