. What is the mass of an object if it is pulled by a 5 Newton force and it accelerates at a rate of 20 m/s/s? Please help ASAP

What is the magnitude of the resultant vector round your answer to the nearest tenth

A15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°c to 175°c. what is the specific heat capacity of iron?

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.