Question

A force exerted on an object produces an acceleration. If the mass remains the same and the acceleration is doubled, the force must be
quadrupled
halved
doubled

Jupiter's gravitational field at the surface is approximately three times that of the earth. A person weighing 120 lb. on the earth's surface would weigh how much on Jupiter?
weight does not change
360
40


Planet A takes one year to go around the sun at a distance of one A U. (astronomical unit). Planet B is three A.U. from the sun. How many years does Planet B take to orbit? Choose the closest answer.
3 years
5 years
7 years
9 years

Answer 1

A
The formula is F = m*a. It looks like a direct variation. m is held constant so as a increases, so does F. The answer is if a is doubled so is F.

Doubled <<<<< answer.

B
Jupiter has a gravitational pull 3 times that of earth. If a person weighs 120 pound on earth, he will weigh 3*120 = 360 on Jupiter. The answer is not 40, that's for sure.

360 pounds on Jupiter <<<<< answer.

C
In the solar system the time taken for Mercury to orbit the sun is 88 days. The earth takes 365 days. The distances are 58 million miles and 150 million miles. The distance is about 3 times as far for the earth as it is for Mercury. Though not a very close approximation the time's ratio is roughly 3 times as much, perhaps 4 but that is not an option. Pick 3.

A<<<< answer. 

Answer 2

Answer:

1)  doubled

2) 360 lb

3) 5 years

Explanation:

1) F = ma  clearly shows that for a given mass, more force implies more acceleration,  If force is doubled, acceleration is also doubled.

2) Since weight is the gravitational force , F = mg becomes 3 mg on Jupiter because its gravitational field is 3 times that on earth.

3) Kepler's 3rd law gives a relation between time period and distance(radius of orbit) .$T_{1}^{2} \div  T_{2}^{2} = R_{1}^{3} \div R_{2}^{3}$

So 3 times the radius of orbit gives the  time period as square root of 27, which is 5.2.