1. (a) Explain on the basis of conservation of momentum, how a fish propels itse

Question

1. (a) Explain on the basis of conservation of momentum, how a fish propels itself forward by swishing its tail back and forth. (b) In a collision between two cars, which would you expect to be more damaging to the occupants: if the cars collide and remain together, or if the two cars collide and rebound backward? Explain. (c) At a hydroelectric power plant, water is directed at high speed against turbine blades on an axle that turns an electric generator. For maximum power generation, should the turbine be designed so that the water is brought to a dead stop, or so that the water rebounds? (d) If only an external force can change the momentum of the center of mass of an object, how can the internal force of the engine accelerate a car?

Explanation / Answer

Part a

when fish propels itself forward then by conservation of momentum it get velocity in the forward direction. momentum of water increase in backward direction so momentum of fish increase in forward direction.

Part B

If car collid and remain together then damage is more as more energy lost in collision as it is perfectly inelastic collision.

Part C

If water comes to a dead stop then its momentum transferred to generator blades and they rotate but if it rebounds then momentum transferred is doubled as direction of water changes after striking blades. so rebound of water is more effecient option.

Part D

Car is accelerated due to burning of fuel which generated gaseous mixture which comes out of the car. as mass is coming out of car in backward direction its momentum increase in forward direction. so a car accelerates.

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