URGENT Problem
A student places a steak on one side of a double balance pan. She adds weights of known mass to the other side until both sides are balanced.
Then, she eats three fourths of the steak and places it back on the scale.

Figure 1: Double balance pan. Image from Wikimedia Commons, CC0 1.0.
How can she find gravitational mass of the steak ?
Assume all the weights of known mass are equal.

Two cannon balls weighing 18 kg and 24 kg are chained together and fired horizontally with a velocity of 165 m/s from the top of a 21-m wall. the chain breaks during the flight of the cannonballs and the 18-kg cannonball strikes the ground at t = 1.5 s, at a distance of 240 m from the foot of the wall, and 7 m to the right of the line of fire. determine the position of the other cannonball at that instant. neglect the resistance of the air.