A) 1.35 J
Explanation:
The work done by gravity on the coin is equal to the force F applied (which is equal to the weight of the coin) times the height of the fall, d:
The weight of the coin is:
And using d=25 m, we find the work done:
B) 22.5 m/s
Explanation:
this is a uniformly accelerated motion, with constant acceleration g=9.81 m/s^2, so the velocity of the coin can be found by using the following SUVAT equation
where
v is the final velocity of the coin
u=4.0 m/s is the initial velocity of the coin
a=9.81 m/s^2 is the acceleration
d=25 m is the heigth of the fall
Using the equation, we find