Power Transfer Lift
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Power Transfer Lift
energy transfer and efficiency questions, please help
?please help me with these questions i don't understand them
1.An electrical kettle has a power rating of 2kW and i switched on for 100 seconds.
While heating up, it looses 60,000 joules to the surroundings.
a) how much energy is supplied to the kettle
(1 kW = 1000 W = 1000 joules per second)
b) How much is given to the water?
c) What is the efficiency of heating water?
2. An electric motor on a building site has a power rating of 400 W and lifts a load of bricks weighing 600 N through a height of 10m in 20 seconds.
a) how much energy is needed to lie the bricks?
b) how much energy is supplied to the motor in 20 seconds?
c) what is the efficiency of the motor in doing this job?
thanks
1. 2kw for 100 seconds = 2000 w x 100s = 200,000 Joules total
60,000 is lost
leaving 140,000 Joules for the water
Efficency = 140000/200000 = 70%
2.
a = Newtons * distance = 600 x 10 = 6000 Joules
b = Watts x Time = 400 * 20 = 8000 Watts = 8000 Joules
c = 6000 / 8000 = 75%
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ELECTRICAL POWER TRANSFER W/ $328.99 ELECTRICAL POWER TRANSFER W/ |
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Power Lift $113.99 PowerMadd Power Lift Easily lift the front or rear of any snowmobile with one hand Has a lifted height range of 18"-31" Extends belt life and prevents track freeze up Lift the snowmobile a total of 7" Lift the bumpers from as low as 11" off the ground Durable powder coated steel construction |
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Transfer of Power $7.3 No Synopsis Available |
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Transfer Case Lowering Kit by Skyjacker for Jeep $39.59 Fits 1997 to 2002 TJ Wrangler with 2-2.5" lift JEEP WRANGLER (97-06TJ) SAHARA SE SPORT 1997 1998 1999 2000 2001 2.5L (150) 4L Power Tech (242) GAS Transfer Case Lowering Kit by Skyjacker for Jeep |
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HP BACKPLANE/POWER Transfer Board SAS 411794001 $35.93 HP BACKPLANE/POWER Transfer Board SAS 411794001 |
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Transfer Case Lowering Kit $72.99 Transfer Case Lowering Kit; 4 in. Lift; Black Powder Coat; |
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Transfer Case Lowering Kit by Pro Comp for Jeep $62.99 1987-02 Wrangler;1 in. total drop;For vehicles with 2-4 in. of lift JEEP WRANGLER (87-95YJ) WRANGLER (97-06TJ) ISLANDER LAREDO RENEGADE RIO GRANDE S SAHARA SE SPORT X 1987 1988 1989 1990 1991 1992 1993 1994 1995 1997 1998 1999 2000 2001 2002 2.5L (150) 4.2L (258) 4L Power Tech (242) GAS Transfer Case Lowering Kit by Pro Comp for Jeep |
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Transfer Case Drop Kit by Trail Master for Jeep $33.99 1976-86 Jeep CJ;Correct driveline angles;Works with 3 in. or more lift;Includes instructions and all hardware needed for installation JEEP WRANGLER (87-95YJ) WRANGLER (97-06TJ) ISLANDER LAREDO RENEGADE RIO GRANDE S SAHARA SE SPORT 1987 1988 1989 1990 1991 1992 1993 1994 1995 1997 1998 1999 2.5L (150) 4.2L (258) 4L Power Tech (242) GAS Transfer Case Drop Kit by Trail Master for Jeep |
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Hoyer lift - Resident Transfer Bed to Wheelchair and Wheelchair to Bed
Someone pleaseee help me with these 4 physics problems, PLEASE!?
A 60.9 kg pole vaulter runs at 7.51 m/s and plants her pole. She puts all of her kinetic energy into the pole, which bends and then gives back her energy in the form of potential energy. Assuming a 100% transfer of energy, how high does the pole lift her?
Oliver's 1400-kg sports car accelerates from rest to 136.1 km/hr in 11.9 s. What is the average power in hp delivered by the engine? (1 horsepower = 746 watts)
Stuart fires a 9.4 g bullet at a ballistic pendulum whose bob weighs 1.5 kg. The bullet imbeds into the bob which rises 12.5 cm above its lowest point. How fast was the bullet going in m/s when it struck the bob
Michelle hangs a 100 g mass on the end of a spring. When she adds 50 g more, the spring stretches 7.68 cm more. How much would it have stretched in meters if she had added 133.5 g?
The first one is easier said: "How high will an object traveling 7.51 m/s go against gravity 9.8m/s/s before beginning to return downward?
Time =7.51 m/s / 9.8 m/s/s = 0.766 sec
Height= 1/2 9.8 m/s/s Time^2 = 1/2 9.8 m/s's .587 s^2 = 2.88 m
The second one is straight forward and just requires a lot of conversions.
E(total) =1/2 1400 kg (136 km /hr)^2
E = 1/2 1400 kg 136^2 x1000 x 1000 x m^2 / 60 x 60 x 60 x 60 x sec^2
E = 999012 kg m^2/s^2 999012 Joules
Power = E/t = 999012 / 11.9 sec = 83950 Joules/sec = 83950 Watts
83950W / 746W/HP = 112 HP
The third one is easier
The mass of the pendulum and the bullet is raised distance 12.5 cm. The energy of the bullet is stored in the total mass of the pendulum and the bullet raised against gravity
E = Force x distance
E = Gravitation x mass x distance
E = 9.8 m/sec^2 x (1.5 + 0.0094) kg x 12.5 cm x 1 m/100cm
E = 1.8 kg m^2/sec^2
E = 1/2 mv^2= 1/2 m (bullet) v( bullet)^2 = 1/2 0.0094 kg v^2
1.85 kg m^2/sec^2 = 1/2 x 0.0094 kg v^2
2 x 1.8 kg m^2/sec^2 / 0.0094 kg = v^2
393 m^2/sec^2 = v^2
19.8 m/s = v
The tension on the string is the sum of the weights.
The deflection of the string due to adding 50 grams is 7.68 cm or 0.1536 cm/gram
The deflection due to 133.5 gram should be 0.1536cm /gram x 133.5 gm =20.5 cm assuming the string responds linearly.
