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Old Apr 11th 2013, 08:34 PM   #1
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A 400g lemming waddles horizontally...

A 400g lemming waddles horizontally off a small 4.9m high cliff with a horizontal velocity of 0.5m/s.
a) How far from the base of the cliff will the lemming land?
b) What will be the lemming's speed just before landing?
c) What is the lemming's kinetic energy just before landing?

Any help will be appreciated.
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Old Apr 12th 2013, 07:01 AM   #2
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The process to use here is:

1. calculate the time it takes for the lemming to fall 4.9 meters, using d = (1/2)gt^2. Then the horizontal distance traveled in that time comes from d = v_x t, where v_x is the horizontal velocity,

2. Speed is the magnitude of the vector sum of the horizontal plus vertical components of velocity, v_x + v_y. You already have v_x. V_y can be found from v_y = gt. Use Pythagoras to find the magnitude of their sum.

3. KE = (1/2) mv^2, using the velocity you calculated above.
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