Explain why the books will not slide down the ramps at the same speed.

a. the sandpaper ramp will have more friction than the wood ramp.

b. the book on the wood ramp has more gravity pulling on it.

c. the wood ramp will have more friction then the sandpaper ramp.

d. the sandpaper ramp is higher than the wood ramp.

explain why you choose the answer you did.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?

Which of the following statements accurately describes the sign of the work done on the box by the force of the push? a. positive b. negative c. zero