A42 kg object goes from rest to 23 m/s, what is the magnitude of the force if it accelerates in .67 seconds?

Force = mass x acceleration 
we need 1st to get the acceleration 
acc= velocity / time 
acc= 23 / 0.67 
acc = 34.33 m/s^2 
by subs. in the first law 
F= 34.33 * 42 
Force = 1441.79 N 

Force is equated as the product of mass and acceleration (F = ma). Since mass (m = 42kg) is already given, we only need to look for acceleration.

Acceleration can be obtained by dividing velocity by time. From that, we substitute the given values of t = .67s and v = 23m/s

a = v / t
a = (23m/s) / .67s
a = 34.33 m/s^2

Since we now have the value of a, we substitute it to the formula for force:

F = 42kg x 34.33 m/s^2
F = 1441.8 N