Question

Polly is pushing a box across the floor with a force of 30N the force of gravity is -8N and the normal force is 8N which value could describe the force of friction if polly could not move the box

A. -30N

B. -8N

C. 8N

D. 30N

Answer 1

30N. Polly is pushing a box across the floor with a force of 30N the force of gravity

Answer 2

A)
`F_f = -30 N`

Step-by-step explanation:

As we know that box is not moving on the floor

so here net force on the box must be balanced

so in horizontal direction as well as in vertical direction net force must be zero

so we can say in vertical direction we have two forces

1) Normal force

2) weight

so we have

`F_n + F_g = 0`

`8 - 8 = 0`

similarly in horizontal direction we have

1) Applied force

2) friction force

`F_(applied) + F_(friction) = 0`

`30 + F_f = 0`]

`F_f = -30`