automative lif rasise a 3500lb car 7ft above floor level if the hydraulic cylinder contain 8in diameter piston?

An automotive LIFOtraisese a 3500lb car 7ft above floor level if the hydraulic cylinder contain 8in diameter piston and a 4in diameter rod,determine the
A. work necessary to lift the car
B. required pressure
C. power if the lift raises the car 10 s
D. Descending speed of the lift for a 10-gpm flow rate
E. flow rate for the auto too descend in 10 s

Chosen Answer:

All these answers based on 8 inch lifting cylinder. You haven’t specified anything about the 4 inch rod so haven’t used that in these answers

a). work = force x distance
work = 3500 lb x 7 ft = 24,500 ft-lbs of work
————————————————-
b) 8 inch diameter piston = area of pi * r^2 = 50.26 sq inches
3500 lb / 50.26 in^2 = 69.6 psi pressure
——————————————–
c) power = work / time = 24,500 ft-lbs / 10s = 2450 ft-lb/ second
(one foot-lb /second = 0.738 watt so –> 2450 * .738 = 1,808 watts of power in SI system)
—————————————————————-
d) volume of a cylinder = pi * radius squared * height
one gallon = 231 cubic inches
10 gallons = 2,310 cubic inches
V =2,310 cubic inches = 3.14 * 4in ^2 * height
height = 2310 / (pi * 16) = 45.96 inches

So 10 gallons a minute will lift car or descend car 45.96 inches or 3.8 feet a minute
————————————————————————————————–

e) Flow rate to descend in 10 seconds instead of a minute is 6 times faster (60 sec a minute / 10 sec) = 6.
6 * 10gpm = 60 gpm
.
by: biire2u
on: 14th April 10

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MORE PHYSICS PROBLEMS HELP!? 10 POINTS!?

1) what’s the kinetic energy of a 2kg toy car moving at a velocity of 5 m/s?
A. 5 J
B. 10 J
C. 25 J
D. 50 J

2) a 50 kg firefighter is on a ladder 10 meters above the ground. when the firefighter descends to 5 meters above the ground, the firefighter’s gravitational potential energy will decrease by
A. 0.194 joules
B. 5.10 joules
C. 490 joules
D. 2450 joules

3)a hydraulic lift used at an automotive repair shop raises a 1000 kg car two meters off of the ground. what is the potential energy given to the car?
A. 1000 J
B. 2000 J
C. 9800 J
D. 19,600 J

4) a 5 kg mass is lifted from the ground to a height of 10 meters, the gravitational potential energy of the mass is increased by approximately
A. 0.5 J
B. 50 J
C. 250 J
D. 500 J

5) a high diver steps off a diving platform that is 10 meters above the water. if no air resistance is present, during the fall there will be a decrease in the diver’s
A. gravitational potential energy
B. total mechanic energy
C. kinetic energy
D. momentum

Chosen Answer:

1. C kinetic energy = i/2 mass (velocity)2
2.D gravitational potential energy is =mgh where m = mass,g= 9.8m/s2 and h is height it descends to 5 that’s why the answer is 2450J
3.answer is letter D 19600J the formula is P.E = mgh
4.the answer is letter D value of g varies other use the original value 9.8 m/s2 while Other can also use 10m/s2 in case of number the value use is 10m/s2.
5. A
by: len
on: 4th May 09