(a) A battery lights a bulb. Describe the energy changes involved in the process.
(a) A battery lights a bulb. Describe the energy changes involved in the process.
(b) Calculate the amount of work needed to stop a car of 500 kg, moving at a speed of 36 km/h.
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(a) Energy conversion:
Chemical energy of battery → electrical energy → heat and light energy.
(b) Given,
Mass of a car, m = 500 kg,
Speed of car, v = 36 km/h = 10 m/s
Work needed to stop a car = K.E. of the car
Therefore,
K. E. = 1 /2 mv2
= 1 /2 × 500 × 102
= 25000 Joule
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