1) A car is traveling down the interstate at 37.1 m/s. The driver sees a cop and quickly slows down. If the driver slows to 29.8 m/s in 3 seconds, what is the acceleration of the car?

2) While cleaning you lift an 87.3 N box up to a shelf that is 2.04 m above the ground. How much work was done on the box?

3) A child runs up the stairs and does 1250 J of work. If the child generates 267 W of power how long did it take for the child to run up the stairs?

Explanation:

1. Acceleration is the change in velocity over time.

a = Δv / Δt

a = (29.8 m/s − 37.1 m/s) / 3 s

a = -2.43 m/s²

2. Work equals force times distance.

W = Fd

W = (87.3 N) (2.04 m)

W = 178 J

3. Power is work per time.

P = W / t

267 W = 1250 J / t

t = 4.68 s

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.