A car has wheels of radius of 0.380 m and they rotate once every 0.100 s. What is the linear velocity of the wheels? (Units = m/
2 answers:
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Answer:
0.278 m/s
Explanation:
We can answer the problem by using the law of conservation of momentum. In fact, the total momentum before the collision must be equal to the total momentum after the collision.
So we can write:
where
m = 0.200 kg is the mass of the koala bear
u = 0.750 m/s is the initial velocity of the koala bear
M = 0.350 kg is the mass of the other clay model
v is their final combined velocity
Solving the equation for v, we get
Answer:
Approximately (rounded down,) assuming that
.
The number of repetitions would increase if efficiency increases.
Explanation:
Ensure that all quantities involved are in standard units:
Energy from the cookie (should be in joules, ):
.
Height of the weight (should be in meters, ):
.
Energy required to lift the weight by without acceleration:
.
At an efficiency of , the actual amount of energy required to raise this weight to that height would be:
.
Divide by
to find the number of times this weight could be lifted up within that energy budget:
.
Increasing the efficiency (the denominator) would reduce the amount of energy input required to achieve the same amount of useful work. Thus, the same energy budget would allow this weight to be lifted up for more times.