A motorcyclist is traveling at 58.3 mph on a flat stretch of highway during a sudden rainstorm. The rain has reduced the coeffic
ient of static friction between the motorcycle tires and the road to 0.070 when the motorcyclist slams on the brakes.
(a) What is the minimum distance required to bring the motorcycle to a complete stop?
(b) What would be the stopping distance if it were not raining and the coefficient of static friction were 0.580?
(a) What is the minimum distance required to bring the motorcycle to a complete stop?
(b) What would be the stopping distance if it were not raining and the coefficient of static friction were 0.580?
1 answer:
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Answer:
Approximately .
Explanation:
Let the increase in the rocket's velocity be . Let
represent the initial velocity of the rocket. Note that for this question, the exact value of
doesn't really matter.
The momentum of an object is equal to its mass times its velocity.
- Mass of the rocket with the 5 kg of fuel:
.
- Initial velocity of the rocket and the fuel:
.
- Hence the initial momentum of the rocket:
.
- Mass of the rocket without that 5 kg of fuel:
.
- Final velocity of the rocket:
.
- Hence the final momentum of the rocket:
.
- Mass of the 5 kg of fuel:
.
- Final velocity of the fuel:
(assuming that the the 500 m/s in the question takes the rocket as its reference.)
- Hence the final momentum of the fuel:
.
Momentum is conserved in an isolated system like the rocket and its fuel. That is:
Sum of initial momentum = Sum of final momentum.
.
Note that appears on both sides of the equation. These two terms could hence be eliminated.
.
.
Hence, the velocity of the rocket increased by around 2.5 m/s.