1. Efficiency of a machine equals   Work Output / Work Input × 100 %   Work Output / (Work Input + Work Output) × 100 %   Work Input / Work Output × 100 %   Work Input / (Work Input + Work Output) × 100 %   Hint Half-n-half Clue   2. A mass of 40 kg is moved vertically upwards through a distance of 11 m. If the gravitational acceleration is 9.8 m s-2, then the work done against gravity is   107.8 J   440 J   392 J   4312 J   Half-n-half Clue   3. A mass of 3 kg is raised through a vertical distance of 60 m. If the gravitational acceleration is 9.8 m s-2, then the potential energy gained by the mass is   180 J   1764 J   588 J   29.4 J   Half-n-half Clue   4. A body loses 2401 J of potential energy in falling through 35 m. If the gravitational acceleration is 9.8 m s-2, then the body has a mass of   343 kg   69 kg   7 kg   245 kg   Half-n-half Clue   5. The energy possessed by a body due to its position or configuration is called _______ energy.   potential   thermal   sound   kinetic   Half-n-half Clue   6. If there is no friction, the efficiency of a machine can be greater than 100 %.   True   False   7. When a current is supplied by a battery, _______ energy is converted to electrical energy.   mechanical   chemical   nuclear   Half-n-half Clue