1.A light aluminum ball and a heavy lead ball of the same size are allowed to roll down an incline. When they are halfway down the incline, they will have identical
a. potential energies.
b. kinetic energies.
c. momentum.
d. inertias.
e. none of the above choices
2.The difference between impulse and impact force involves the
a. difference between acceleration and velocity.
b. mass and its effect on resisting a change in momentum.
c. distance the force acts.
d. time the force acts.
3.If you push an object a given distance, while applying twice the force, you do
a. twice as much work.
b. four times as much work.
c. the same amount of work.
d. half as much work.
4.You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact?
a. the bug
b. your car
c. both the same
5.A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both move with a combined momentum of
a. more than 1 unit.
b. 1 unit.
c. less than 1 unit.
d. not enough information
6.A car traveling along the highway needs a certain amount of force exerted on it to stop it in a certain distance. More stopping force is required when the car has
a. more momentum.
b. more mass.
c. less stopping distance.
d. all of these
e. none of these
7.A pile driver hits the top of a telephone pole driving it partway into the ground. The distance that the pole will sink into the ground depends on
a. the kinetic energy of the pile driver weight when it first contacted the pole.
b. the original potential energy of the pile driver.weight.
c. the original height of the pile driver weight.
d. any of the above choices
Urgent Phy Q....Help Help Help!!!
2008-10-27 1:11 am
回答 (1)
2008-10-28 3:58 am
✔ 最佳答案
1. E. None of the above.At that moment, they have the same height and same velocity. However, their mass are not the same, so A, B and C are not correct.
Mass is the measurement of inertia. Their masses are not the same. So D is wrong.
2. D.
Impulse is the rate of change of momentum, it also equals force X time.
3. A.
Word done = Force X distance. Force is twice, distance remains unchanged. Work done is doubled.
4. C
According to Newton's 3rd law of motion, the force exerted on the car by the bug and the force exerted on the bug by the car are action and reaction pairs.
5. B
There is no external force acting on the system, so the total momentum of the system is conserved.
6. D
More stopping force implies the deceleration is larger.
When deceleration is larger, for the same initial velocity, the stopping distance is shorter.
Or for the same stopping distance, the initial velocity is larger, which implies the initial momentum is also larger.
7. D
By the law of conservation of energy, the loss of G.P.E. of the pile driver is converted to its K.E. and then converted to the work done of the pole against the friction due to the ground.
參考: Myself~~~
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