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I have some questions about physics? 1. A baseball is moving at 31 m/s East when it is...

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leesterine | eNotes Newbie

Posted September 22, 2013 at 10:08 PM via web

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I have some questions about physics?

1. A baseball is moving at 31 m/s East when it is struck by the bat and moves off in the opposite direction at 35 m/s. If the impact lasted 0.010s, find the baseball's acceleration in m/s^2 during the impact. 

2. A shopping cart given an initial velocity at 2.0 m/s East undergoes a constant acceleration of 3.0 m/s^2. What is the cart's displacement after the first 5.0s of its motion? 
3. An airplane must have a velocity of 50 m/s in order to take off. What must the airplane's acceleration be if it is to take off from a runway 0.45 km long?
4. 2 part question: Amanda is running away from Ben. Both are travelling at a constant speed. Amanda's speed is 1.5 m/s and Ben's speed is 2.2 m/s. Amanda gets a 30s head start.
a. Determine how long it takes for Ben to catch up to Amanda. 
b. Determine the distance traveled when Ben catches Amanda. 

1 Answer | Add Yours

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ishpiro | Teacher | (Level 3) Associate Educator

Posted September 23, 2013 at 2:37 AM (Answer #1)

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The formula for the displacement is

`d=v_0t + (at^2)/2` , where `v_0` is the initial velocity, a is the acceleration and t is the time elapsed from the beginning of the motion.

So after t = 5 s, assuming acceleration is in the same direction as the initial velocity (even though it is not really stated in the problem), the  displacement will be

`d=2*5 + (3*5^2)/2 = 10+37.5 = 47.5` meters.

The displacement after 5 seconds of motion will be

d = 47.5 meters.

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