A seal swims rightward 3 m, but then notices a shark behind it. The seal speeds up rightward for 12 m and swims a total time 4 s.

3 m

12 m

What is the seal's average velocity for the swim?

2.25m/s

Explanation:

Average velocity is the change in displacement of a bod with respect to time;

Velocity = Δd/Δt

velocity = d₂-d₁/Δt

Given d₂ = 12m, d₁ = 3m and Δt = 4s

Substitute the given value into the fromula;

velocity = 12-3/4

velocity = 9/4

velocity = 2.25m/s

Hence the seal's average velocity for the swim is 2.25m/s

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.