1. If there is no friction, the efficiency of a machine can be greater than 100 %.   True   False   2. By definition, work is done when a _______ moves through a distance.   mass   pressure   force   Hint Half-n-half Clue   3. A carton is pulled along the ground for a distance of 8 m. If the average frictional force is 87 N, then the work done is   8 J   87 J   696 J   5568 J   Half-n-half Clue   4. The SI unit of power is   Volt   Watt   Joule   Half-n-half Clue   5. A boy throws a ball vertically upwards from ground level. If the ball reaches a maximum height of 250 m and the gravitational acceleration is 9.8 m/s2, with what speed did the boy throw the ball?   50 m/s   10 m/s   35 m/s   70 m/s   Half-n-half Clue   6. A machine that produces 91 J of work by using 140 J of energy has an efficiency of   49 J   65 %   13 J   35 %   Half-n-half Clue   7. Both work and heat are measured in Joules.   True   False