Worksheet 10 soln - Practice probs for phys PDF

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Practice probs for phys...

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Potential and Kinetic energy: Worksheet 10 1.You serve a volley ball with a mass of 2.1kg. The ball leaves your hand at 30m/s. a. What type of energy does the ball have? Kinetic energy b. Calculate this energy. Ek = 0.5mv2 = 0.5 x 2.1 x 302 = 945 J 2.There is a bell at the top of a tower that is 45m high. The bell weighs 190N. a. What type of energy does the bell have? Potential Energy b. Calculate this energy Ep = mgh = 190 x 45 = 8550 J 3.The potential energy of an apple is 6.0 joules. The apple is 3m high. What is the mass of the apple? Ep

m = gh

6

= 10 x 3 =0.2 kg

4.What is the velocity of a 500kg elevator that has 4000J of energy?

v=

√

Ek 0.5 m

= 4m/s

5.What is the mass of an object that creates 33,750J of energy by traveling at 30m/s?

m=

Ek 0.5 v 2

=

33750 0.5 x 302

= 75 kg

6.Calculate the speeds a 1.0 kg mass and then a 2.0 kg coconut will reach when falling to the ground from 25 m. What do you notice? Assume all Ep is transferred to Ek a. Ep = mgh = 1 x 10 x 25 = 250 J. Thus Ep = Ek v=

√

Ek 0.5 m

√

Ek 0.5 m

=

√

250 0.5 x 1

√

500 0.5 x 2

=22.4 m/s

b. Ep = mgh = 2 x 10 x 25 = 500 J. Thus Ep = Ek v=

=

=22.4 m/s

7.An Airbus A380 jet aircraft has a fully loaded mass of 550 000 kg. it can travel at a height of 12 km with a speed of 250 m/s a. How much kinetic energy does it have? Ek = 0.5mv2 = 0.5 x 550000 x 2502 = 1.7 x 1010 J

b. How much gravitational potential energy does it have? Ep = mgh = 550000 x 10 x 12000 = 6.6 x 1010 J....