Answer:
F = 120 N
Explanation:
Force x distance = energy
The bike has energy 1/2 . 80 . 6^2 = 1440 J
You are looking at an example of not reading the question properly.
Impulse = Force . time = change in momentum
F . 4 = 80 .6
F = 120 N
Answer:
45.6m
Explanation:
The equation for the position y of an object in free fall is:

With the given values in the question the equation has one unknown v₀:

Solving for t=1:
1) 
To find the hight of the tower you can use the concept of energy conservation:
The energy of the body 1 sec before it hits the ground:
2) 
If h is the height of the tower, the energy on top of the tower:
3) 
Combining equation 2 and 3 and solving for h:
4) 
Combining equation 1 and 4:

Vf = 0 + 3.5•8.7
= 30.45 m/s
Of the following...?? Is there more to this question? :)