Determina la magnitud de la fuerza que se debe aplicar a un sillón cuya masa es de 40 kg para que adquiera una aceleración con magnitud de 3 m/s²

Can anybody me with this? ? (picture included.)

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.

What types of radiation make up the electromagnetic spectrum?