A 80.0 kg person on rollerblades pushes against a 700. Kg box on wheels with a force of 50.0 N and they roll away from each other. The person accelerates to the left and the box accelerates to the right.

 person a₁ = -0.625 m / s², box a₂ = 0.0714 m / s²

Explanation:

In this exercise we have a problem of action and reaction forces, the force with which the person (action) pushes the box is of the same magnitude as the force with which the box (reaction) pushes the person, but in the opposite direction.

We work that body separately

Person

           -F = m₁ a₁

             a₁ = -F / m₁

             a₁ = -50.0 / 80.0

             a₁ = -0.625 m / s²

the negative sign means that the person moves away from the box

Box

            F = m₂ a₂

            a₂ = F / m₂

            a₂ = 50.0 / 700

            a₂ = 0.0714 m / s²

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)

this would be about 43%