Work, Energy & Power Quiz  Mechanical Energy  Work  Power  Conservation of Mechanical Energy  Mechanical Efficiency

1. Which of the following is a form of mechanical energy? a) thermal energy b) solar energy c) translation kinetic energy d) chemical energy

2. How much work is done to rise from a seat if the 45.0 kg person raises herself 35 cm? a) J b) J c) 1575 J d) 1545 J

3. How much energy does it take to stop a 5 kg projectile that is travelling at 65 m/s? a) J b) 325 J c) kJ d) 21.2 kJ

4. Which of the following forces is NOT conservative? a) rigid lever and fulcrum b) friction of a level surface c) ideal spring d) tension in an ideal pendulum wire

5. Which of the following is NOT an equation for computing mechanical power? a) P = M  b) P = W t c) P = E / t d) P = F. v

6. What is the instantaneous power of a knee that exerts a 150 N force against a 35 cm lever that is rotating at 120 deg/s? a) 110 W b) 6300 W c) kW d) kW

7. How high must a 10 kg projectile be raised to achieve a velocity of 5 m/s when it is dropped? a) m b) m c) 2.55 m d) m

Answers 1.c (translational kinetic) 2.b (45 x 9.81 x 0.35) 3.c (1/2 x 5 x 65 2 ) 4.b (friction is non-conservative) 5.b (P = W / t; P ≠ W t) 6.a (150 x 0.35 x 120 x /180) 7.d (y = v 2 /2 g = 5 2 /[2 x 9.81])