Work and Energy HELP PLEASE?

Question

A 300 N Force pushes a 120 kg box on a smooth(no friction) surface. If the Force is applied during 8 seconds, determine the work done by the force.

I don't know how to get the answer because no formula can help. Can someone help me do this by showing me step by step solution. HELP PLEASE

Answer 1

The equations you need are

work W = f.s

Newton's law f = m.a

and the distance covered by an initially stationary object moving at a constanct acceleration a, s = a.t^2 /2

Now you have

W = f.s

= f.(a.t^2 /2)  [assuming the box is at rest before the force is applied]

= f.(f/m).t^2 /2

W = f^2.t^2 /2m

now plug the numbers in

W = 300^2.8^2 / (2.120) = 24 000 J

Answer 2

Use F = ma to calculate the acceleration a = 300/120 = 2.5m/s^2  then the distance covered in 8 seconds is (at^2)/2 = 80 meters so now you can use the equation W = F d = 300 * 80 = 24000 joules.

Answer 3

F=ma so a=F/m

a=300N/120kg

a=2.5m/s²

Δx=v₀t+½at²

Δx=(0)(8s)+½(2.5m/s²)(8s² )

Δx=(0)+½(2.5m/s²)(64s²)

Δx=½(160m)

Δx=80m

W=Fd

W=(300N)(80m)

W=24,000J

Answer 4

Work (j) = force x displacement.

            = 300 x dispacment.

f= m. a

300 = 120.acceleration

a = 300/120 = 2.5m/s/s

s or displacement = 1/2 at^2

                           = 0.5 x 2.5 x 8^2

                           = 80m

therfore work done (j) = 300 x 80 = 24000j or 24 kj