netwon's laws of motion

Question

A force of 250 N is used to push a heavy box down the street. If the force of friction between the box and the street is 195 N and the box has a mass of 60 kg, what is the acceleration of the box?

2. A force of 40 N is applied to a 6 kg box of books. If the frictional force acting on the box is 16 N, and the box was initially at rest, what is the velocity of the box 10 s later? What is the box’s displacement over the 10 s period?

Answer 1

Problem 1)

250 N - 195 N = 55 N

F = ma

55 = (60)s

a = 55/60 = 0.92 m/s²

Problem 2)

40 - 16 = 24 N

F = ma

24 = 6a

a = 4 m/s²

Using v_f = v_i + at where v_i = 0 (the object is initially at rest), t = 10 s and a = 4 m/s²"

v_f = 0 + (4)(10) = 40 m/s

The displacemnt is calculated using x = v_it + (1/2)at²

x = (0)(10) + (1/2)(4)(10²) = 0 + 200 = 200 meters