Question

What force is required to accelerate a 90kg bike to 20 m/s in 15 sec?

I need to know HOW to do it!

Answer 1

first, recall formula for Force:

F = ma
where m = mass in kg, and a = acceleration in m/(s^2)

then also recall the formula for acceleration,,
acceleration is change in velocity over time, thus:
a = (v - v0)/t
where v = final velocity in m/s
v0 = initial velocity in m/s
t = time in s
since you are you are given velocity and time, calculate for a first,, assuming the bike is initially at rest, v0 = 0:
a = (v - v0)/t
a = 20/15 = ? *solve this*

after that, substitute this to
F = ma
since you are also given the mass, you can solve for F.

hope this helps.