Physics Problem (Newton's Laws)?

Question

A car weighs 1.15 x 10^4 N. A force of 895 N is used to accelerate the car from rest to 25 m/s. How much time is required for the acceleration? ( ans. 33 secs )

can anyone help how the answer is solved?

Answer 1

If it weighs 1.15 x 10^4 N, then you can find the mass.

W = mg

m = W/g = 1.15 x 10^4/9.80 m/s^2 = 1170 kg

From N2, you know

F = ma

a = F/m = 895 N/1170 kg = .763 m/s^2 (Note: This is ignoring any effects of friction. Bad assumption, but the only one we can use right now.)

Now you have an initial velocity (0), a final velocity, and an acceleration. You should be able o get the time from that.