I am not sure what all information I need to include in this question. If I need

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I am not sure what all information I need to include in this question. If I need more info or less please let me know for future questions.

My question comes from a text book solution in College Physics 1st edition Chapter 1 problem 65P ***part C only. “You accidentally drop an eraser out the window of an apartment 15 m above the ground.

a. how long will it take for the eraser to reach the ground? Answer 1.75s

b. What speed will it have just before it reaches the ground? Answer 17.1 m/s

c. if you multiply the time interval from answer a) by the speed answer b), why is the result much more than 15 m? Answer is 30 m.

however I dont understand why this is. The worked out solution says “therefore, the result is more more than 15m because of horizontal component of velociy is greater than the downward velocity.” this dosnt make sense to me. If you could explain this or give me a better clue on where to I can look up more about this answer. Thank you in advance.

Explanation / Answer

part c:

initial speed was 0 and speed gradually increases with an acceleration of 9.8 m/s^2 which is equal to acceleration of gravity.

if speed were constant, then speed*time taken=distance covered

but as speed is not constant, it is not the correct formula to calculate distance covered.

instead, correct formula is initial velocity*time+0.5*acceleration*time^2

as here initial speed is 0,

distance covered=0.5*acceleration*time^2

which is not same as final velocity*time.

due to the ever changing speed (because of constant acceleration), this occurs.

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