Work and Energy Identify the energy transformation in the following two situatio

Question

Work and Energy Identify the energy transformation in the following two situations. I) An arrow is horizontally 2) A pole vaulter runs, plant her pole, and vaults over the bar 3). A particle moving along the x-axis experiences the force shown in the graph. If the particle has 2 of kinetic energy as it passes r Om, what is its kinetic energy when it reaches x 4m? 1.-20J 2 00 3. 201 4 401 A)-2J B) 0 J C) 2 J D) 4J E)6J (m) 60 4). A 5.0-kg ball on the end of a chain is whirled at a constant speed of 1.0 m/s in a horizontal circle of radius 3.0 m. What is the work done by the tension in the chain during one revolution? A) 2.5J B) 1.7J C) 1.2J D) 0.56 J E) 0 J 5). A particle moves along an x axis. Does the kinetic energy of the particle increase, decrease, or remain the same if the particles velocity changes (a) from-3 m's to -2 m/'s and (b) from -2 m/s to 2 m/s? A) (a) increase(b) increase B) (a) increase (b) stay the same C) (a) decrease(b) decrease D) (a) decrease(b) stay the same E) None of the above

Explanation / Answer

1. first by stretching the wire ( energy is prodcued by chemical potential energy) then this energy is stored as elastic potential energy of stretched wire.

then this elastic energy converts into KE of arro.

Ans: (D)

2. kinetic energy of runer into elastic energy of pole then as height increase, it converts into gravitational PE.

Ans: (A)

3. Work done = changein KE

{ work done = area under F vs x curve}

2 x 4 / 2 = Kf - 2

Kf = 6 J

4. it is moving with constant speed.

and work done = change in KE = 0

Ans(E)

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