A box of mass 45 kg is at rest on a horizontal frictionless surface. A constant horizontal force F then acts on the box and accelerates it to the right. It is observed that it takes the box 7.5 seconds to travel 40 meters. What is the magnitude of the force

F = 64.0 N

the magnitude of the force is 64 N

Explanation:

Given;

Mass m = 45kg

time t = 7.5 s

Displacement d = 40 m

Force = mass × acceleration

F = ma 1

From equation of motion;

d = vt + 0.5at^2

Since initial velocity v = 0 (initially at rest)

d = 0.5at^2

Making a the subject of formula;

a = d/(0.5t^2)

Substituting the given values;

a = 40/(0.5×7.5^2)

a = 1.42 m/s^2

From equation 1;

F = ma

Substituting the given values;

Force F = 45 kg × 1.42 m/s^2

F = 64.0 N

the magnitude of the force is 64 N