The drawing shows two boxes resting on frictionless ramps. One box is relatively light and sits on a steep ramp. The other box is heavier and rests on a ramp that is less steep. The boxes are released from rest at A and allowed to slide down the ramps. The two boxes have masses of 13 and 37 kg. If A and B are hA = 4.4 and hB = 1.7 m, respectively, above the ground, determine the speed of (a) the lighter box and (b) the heavier box when each reaches B. (c) What is the ratio of the kinetic energy of the heavier box to that of the lighter box at B?
I got 2.85 as the ratio, and it right. but cannot get A and B.
I used this for A and B:
mgh = ½mv²
gh = v²/2
v = √(2gh)
v = √(2(9.81)1.7)
v = 5.78 m/s
but it is not right. help me please :(
1 answer
You actually would take √(2gh) and put in √(2)(9.8)(4.4-1.7) and get about 7.27. The speed of the boxes is the same because you don't need mass! :D And good job on getting the ratio! I had a hard time figuring out that you just divided the masses.
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