Answer:
250 N
Explanation:
The acceleration of the 50 kg cart under 750 N of force is:
F = ma
750 N = (50 kg) a
a = 15 m/s²
To accelerate from 13 m/s to 17 m/s takes:
v = at + v₀
17 m/s = (15 m/s²)t + 13 m/s
t = 4/15 s
To accelerate in 3 times as many seconds (t = 4/5 s):
17 m/s = a (4/5 s) + 13 m/s
a = 5 m/s²
So the force is:
F = ma
F = (50 kg) (5 m/s²)
F = 250 N
You could also have reasoned this without the calculations. 3 times the time means 1/3 the acceleration which means 1/3 the force.
