6363

Physics Work,Power & Energy Level: Misc Level

The express elevator in the Sears Tower in Chicago averages a speed of 9.1 m/s in its climb to the 103 rd floor, 410 meters above the ground. Assuming a load of 1.0 x10^3 kg, what average power must the lifting motor supply?

6362

Physics Work,Power & Energy Level: Misc Level

An athlete whose mass is 55.0 kg steps off a 10.0 meter platform and drops onto a trampoline which, while stretching, brings her to a stop 1.00 meter above the ground. Assuming no losses, how much energy must have momentarily been stored in the trampoline as she came to rest?How high should she bounce on the rebound?

6361

Physics Work,Power & Energy Level: Misc Level

A 200g mass attached to the end of a spring causes it to stretch 5 cm. If another 200g mass is added to the spring, the potential energy of the spring will be:the same, 3 time as much, twice as much,4 times as much.

6340

Physics Work,Power & Energy Level: Misc Level

Two men, Joel and Jerry, push against an immovable wall. Jerry stops after 10 min, while Joel is able to push for 5 min longer. Compare the work they do. Who does the most work or do they work at all.

6336

Physics Work,Power & Energy Level: Misc Level

You Lift a 1 Olb physics book up in the air a distance of 1 ft, at constant velocity of .5 ft/s.the work done by gravity is: +5 ft.lb-5 ft.lb zero-10 ft.lb+10 ft.lb

6335

Physics Work,Power & Energy Level: Misc Level

A marathon runner has an average metabolism rate of about 9.5 E2 kcal/h during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 3.4 h.

6277

Physics Work,Power & Energy Level: Misc Level

A simple pendulum with a bob of mass 250 g and length 2.0 m is allowed to fall from a horizontal position. The speed of the bob as it passes the lowest point is: (Assume g=9.8 m//s2)

a. 6.3 m/s

b.39 m/s

c.9.8 m/s

d. 4.9 m/s

6243

Physics Work,Power & Energy Level: Misc Level

Near the surface of the Earth there is an electric field of about 150 V/m which points downward. Two identical balls with mass m=0.540 kg are dropped from a height of 2.0 m, but one of the balls is positively charged with q1=+550 microCoulombs and the second is negatively charged with q2=-550 microCoulombs. Use conservation of energy to determine the difference in the speed of the two balls when they hit the ground. (neglect air resistance)

6234

Physics Work,Power & Energy Level: Misc Level

At the bow of a ship on a stormy sea, a crwman conducts an experiment by standing on a bathroom scale. In calm waters, the scale reads 180 Ib. During the storm, the crewman finds a maximum reading of 224 Ib and a minimum reading of 121 Ib.

(a) Find the maximum upward acceleration experienced by the crewman.m/s2

(b) Find the maximum downward acceleration experience by the crewman. m/s2

6222

Physics Work,Power & Energy Level: Misc Level

A 300 g baseball traveling at 30 m/s is struck by a bat in the direction from which it came at 40 m/s. Find the impulse of the force on the baseball.

a. 12 N/s

b.4.5 N/s

c.21 N/s

d. 18 N/s

6180

Physics Work,Power & Energy Level: Misc Level

Car going down hill. potential energy becomes?Heat or net energy does not change?

6150

Physics Work,Power & Energy Level: Misc Level

an object moving in a circle with constant speed has zero acceleration.

-true- false

6132

Physics Work,Power & Energy Level: Misc Level

A standard automobile b attery is rated at 12 V and 70 ampere hours. Translate those figures into Joules of stored energy. For short periods the battery can deliver a current of 300 A. What is the delivered power in watts?

6062

Physics Work,Power & Energy Level: Misc Level

The work function for metallic caesium is 2.14 eV. Calculate the kinetic energy and the speed of the 4+4=8 electrons ejected by light of wavength a) 750 nm, b)250 nm

6029

Physics Work,Power & Energy Level: Misc Level

A 60 g golf ball is dropped from a height of 2m and rebounds to 1.5 m. How much energy is lost?

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