A falling brick has a mass of 1.5 kg and is moving straight downward with a speed of 5.0 m/s. A 1.5-kg physics book is sliding across the floor with a speed of 5.0 m/s. A 1.5-kg melon is traveling with a horizontal velocity component 3.0 m/s to the right and a vertical component 4.0 m/s upward. Do all of these objects have the same velocity? Do all of them have the same kinetic energy? For both questions, give your reasoning.

Solution 11DQ Step 1: Velocity of freely falling brick, v brick 5 m/s Mass of freely falling brick, m brick 1.5 kg 2 2 2 2 Kinetic energy, KE = ½ mv = ½ × 1.5 kg × 5 m /s KE = ½ × 1.5 kg × 25 m /s = 18.75 Step 2: Velocity of sliding book, v = 5 m/s book Mass of sliding brick, m book= 1.5 kg Kinetic energy, KE = ½ mv = ½ × 1.5 kg × 5 m /s 2 2 2 2 2 KE = ½ × 1.5 kg × 25 m /s = 18.75