Question 4. You are driving your car at 45 mph. Your car has mass 1435kg. You ru

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Question 4. You are driving your car at 45 mph. Your car has mass 1435kg. You run into a car that has mass 1084kg and is going 55 mph in the opposite direction. The two cars lock bumpers, so they move together. No one hits the brakes. How fast will the cars move after the collision? Give your answer in mph to two decimal places.

Correct answer: 1.97

Question 5 (1 point)
If your distance from the center of a planet becomes 0.81 times what it was before, what happens to your weight? Give the answer in terms of the number by which you would multiply your original weight. Express your answer in scientific notation, to three significant figures. E.g. if you move to 3.4 times as far from the center of the planet as you were before, your weight would be multiplied by (1/3.4 squared) = 0.08650519=8.65E-2. This answer has NO units


Correct answer: 1.52E0 (1.52 * 100)


Question 6 (1 point)
If you weigh 232.12 lb on the Earth, what do you weigh at the top of a tower (on Earth) where the tower is 0.22 Earth radii tall. Give your answer in pounds to two decimal places.

Correct answer: 155.95


Question 7 (1 point)
If you weigh 96.6 lb on the Earth. Then the Earth collapses. There is no change of Earth's total mass, and the surface just contracts, but the radius decreases to 0.15 times what it was formally? What do you weigh after the expansion. Tell the number of pounds to two decimal places.

Correct answer: 4293.33


Question 8 (1 point)
If you weigh 142.2 lb on the Earth, what do you weigh on a different planet where the planet has mass 1.0 times as much as Earth's and radius 0.5 times as large as Earth's. Give your answer in pounds to two decimal places.


Correct answer: 568.80


Question 9 (1 point)
What is the smallest velocity that will enable you to escape from the Earth if you are 2.66 Earth radii from the center of the Earth? Give your answer in scientific notation to three significant figures. Remember that the Earth orbits the Sun at 30 km/sec and that satellites at about 1 Earth radius from the center go 7.8 km/sec.


Correct answer: 6.76E0 (6.76 * 100)


Question 10 (1 point)
You hit the 8 ball and it moves East at 3.8 cm/sec. It hits the 3 ball. After the collision, the 8 ball continues to move, but with speed 2.3 in the East direction. How fast does the 3 ball move? Tell the answer to one decimal place and follow it by the direction that it moves.


Correct answer: 1.5


Question 11 (1 point)
A rocket has 556 kg of fuel and 142 kg of solid parts. The fuel exits the rocket at a speed of 4504 meters/second. If the fuel comes out all at one moment, how fast will the rocket be going after the fuel leaves? Assume that the rocket and the fuel were not moving before the fuel left. Use the positive sign for the direction that the fuel goes. Express your answer in scientific notation to three significant figures.

Correct answer: -1.76E4 (-1.76 * 104)

Explanation / Answer

I'll do the first 3: 4. mv final = mv initial 45*1435-55*1084=(45+55)*x Correct answer: 1.97 5. 1/.081^2=152 Correct answer: 1.52E[2]? (1.52 * 100) 6. same way as 5: 232.12*1/1.22^2 (but now 1.22 because 1+height of tower) Correct answer: 155.95 the rest are all just Gm/r^2=weight, see which thing changes.

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