8. A freight elevator with an operator weighs 500 lbs. How much power is require
ID: 1701088 • Letter: 8
Question
8. A freight elevator with an operator weighs 500 lbs. How much power is required to raise it to a height of 50.0 ft in 10 sec? (Points: 6)10 ft-lb/s
450 ft-lb/s
2500 ft-lb/s
5000 ft-lb/s
9. A 60.0 g bullet is fired from a gun and has 3150 J of kinetic energy. What is the velocity? (Points: 6)
229 m/s
324 m/s
1,050 m/s
5,250 m/s
10. The small piston of a hydraulic press has an area of 10.0 cm2. If the applied force is 50.0 N, what is the area of the large piston so that the pressing force is 4800 N? (Points: 6)
96 cm3
480 cm3
960 cm3
4800 cm3
11. A metal block weighs 81 lb in air and 68.0 lb under water. What is the buoyant force of the water? (Points: 6)
13.0 lb
94 lb
149 lb
253 lb
13. The water coolant in a car engine that carries hot water from the engine block to the radiator is an example of cooling by: (Points: 6)
conduction
convection
radiation
transfer
15. A gas occupies 500 in3
at an absolute pressure of 40.0 lb/in2. What is the volume when the absolute pressure is increased to 100 lb/in2? (Points: 6)
400 in3
300 in3
200 in3
50 in3
Anything will help!
Explanation / Answer
8) Power of the elevator = Work/time Power of the elevator = weight*height/time Power of the elevator = 500 lb * 50 ft / 10 s Power of the elevator = 2500 ft-lb/s 9) Speed of the bullet v = sqrt(2KE/m) v = sqrt(2*3150 J/ 0.06 kg) v = 324 m/s 10) Using Pascal's principle F1/A1 = F2/A2 50 N/10 cm^2 = 4800 N/A2 A2 = 960 cm^2 11) The bouyant force = weight in air - weight in water The bouyant force = 81 lb - 68 lb The bouyant force = 13 lb 13)The water coolant in a car engine that carries hot water from the engine block to the radiator is an example of cooling by convection 15) According the ideal gas law P1V1 = P2V2 40 lb/in^2 * 500 in^3 = 100 lb/in^2 * V2 V2 = 200 in^3
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