Question

A student wearing frictionless in-line skates on a horizontal surface is pushed, starting from rest, by a friend with a constant force of 60 N. How far must the student be pushed, so that her final kinetic energy is 300J?

Answer 1

d= 352/45=7.8≈ 8m

Explanation

We can use the Theorem of Work (W) and Kinetic Energy (K):

W=ΔK=k f - k i , it is basically tells us that the work done on our system will show up as change in Kinetic Energy:We know that the initial Kinetic Energy, ki =1/2 mv 2/i, is zero (starting from rest) while the final will be equal to 352J; Work will be force time displacement. so we get: F . d = Ff

45d= 352 and so d= 352/45=7.8 ≈ 8m

Answer 2

Physics

Step-by-step explanation:

Step-by-step explanation:

We can use the Theorem of Work (W) and Kinetic Energy (K):

W=ΔK=Kf−Ki

it basically tells us that the work done on our system will show up as change in Kinetic Energy:

We know that the initial Kinetic Energy, Ki=12mv2i, is zero (starting from rest) while the final will be equal to 352J; Work will be force time displacement. so we get:

F⋅d=Ff

45d=352

and so:

d=35245=7.8≈8m