Suppose you lift a 20 kg box by a height of 10 m a how much...

Suppose you lift a 20 kg box by a height of 1.0 m. a) How much work do you do in lifting the box? Instead of lifting the box straight up, now suppose you push it up a 1.0m high ramp that makes a 30 degree angle with the horizontal. The ramp has no friction. b) How much force F is required to push the box straight up the ramp at constant speed? c) How long is the ramp? d) Use your force and distance results to calculate the work you do in pushing the box up the ramp. How does your answer compare to what you got in part a?

Transcript

00:01 In this problem, we have been given that there is a 20 kg box.

00:05 And this 20 kg box is lifted up to a height of one meter.

00:11 So we need to determine here the work that we do in lifting this box.

00:16 So whatever work is done, that's done against the force of gravity.

00:21 So work should be sufficiently enough to overcome the work done by the gravity.

00:27 So that should be plus mgh.

00:30 So that's 20 times 9 .8 times 1.

00:34 And this comes out to be 196 jules.

00:38 And now here we consider that instead of lifting it directly vertically up, we lift this box with a ramp which is making the angle of 30 degree with the horizontal.

00:53 And this box is lifted up by a 1 meter ramp.

00:58 So we need to determine here the force that's required.

01:03 To push this box above the ramp or up to the ramp at the highest point that we have been given with the constant speed.

01:11 So as the speed is constant, that means the acceleration is zero.

01:14 So that means the force must be equal along both the directions of the incline.

01:23 But nevertheless, we just need to find out the force.

01:28 So here we draw the free body diagram.

01:30 So the weight will be m into g.

01:32 That's 20 times 9 .8, which is.

01:35 Is 19 .6 newtons, 196, because here we have 20 not 2.

01:44 So that will be 196 newtons.

01:47 So if the weight is 196 newtons, we see that there are two components of weight.