(a) how fast must a 3000-kg elephant move to have the same kinetic energy as a 65.0-kg sprinter running at 10.0 m/ s?

1.4719 m per sec

Explanation:

Hello

Kinetic energy is the energy associated with the movement of objects. Although there are many forms of kinetic energy  

the formula to use is

where m is the mass of the object and v the velocity

lets see the kinetic energy of the sprinter running

Now, the elephant must have the same kinetic energy

it works only the positive root, so the elephant must to  walk  to 1.4719 m/s to have the same kinetic energy.

Have a great day

lol

explanation:

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.