Question

MC Question! A box of mass 40kg is pushed in a straight line across a horizontal floor by an 80N force. If the force of kinetic friction acting on the box has a magnitude 60N, what is the acceleration of the box?
A. 0.25 m/s^2
B. 0.5 m/s^2
C. 1.0 m/s^2
D. 2.0 m/s^2
E. 3.5 m/s^2

Answer 1

Answer's B if this helps!

Answer 2

I'm getting 0.05ms/s?

Answer 3

Oh, how are you getting that?

Answer 4

40kg is 40g which is 392N. Using F=ma and realising the net force acting has to be 20N (80-60), the acceleration is 20/392=0.05. It would equal 0.5 if the object weighs 40N not 40kg.

Answer 5

No wait it is B I've made a silly mistake, it makes sense now. acceleration would equal 20/40 which is a half. I'm sorry been a long day!