Physics quiz 3

Which of the following statements about the moon is true?

The moon experiences a centripetal acceleration toward earth

Which of the following statements about the moon is incorrect?

The moon is not accelerating

When cavendish claimed that he weighed earth, he actually calculated the

mass of earth

Al the astronaut has a weight of 800 N when he is standing on the surface of Earth. What is the force of gravity acting on him when he is in a space station orbiting Earth at a distance of three earth radii above the surface?

50 N

The gravitational force between two very large metal spheres in outer space is 200 N. How large would this force be if the mass of each sphere were cut in half?

50 N

The numerical value of G, the gravitational constant, was determined

by measuring the force between masses in labratory

A 90 kg satellite orbits a distant planet with a radius of 4000 km and a period of 280 min. From the radius and period, you calculate the satellites acceleration to be 0.56 m/s². What is the gravitational force on the satellite?

50.4 N

You are standing on a bathroom scale in an elevator that is moving upward at constant speed, when suddenly the cable breaks. From just before to after the cable breaks, the reading on the scale

deceases to zero

Suppose that the planet mercury were magically replaced with a baseball. The magnitude of the net force exerted on the baseball would be

equal to that exerted on Mercury

Suppose that the planet mercury were magically replaced with a baseball. The magnitude of the acceleration of the baseball would be

equal to that of Mercury

If earths mass were suddenly and magically reduced to half its present value, the magnitude of earths acceleration about the sun would

remain the same

For simplicity, a professor uses 9.8 m/s for the acceleration due to gravity instead of the more precise 9.81 m/s. If cavendish had made the same approximation, his estimate for earths mass have been

too low

In a typical 24 hour day, there are

two high tidies and two low tides

Although earths gravitational influence gets weaker with distance, we believe that it extends as far as the

universe extends

During the apollo flights to the moon a well known tv newscaster made the following statement, the apollo space craft is now leaving the gravitational force of earth. This statement is incorrect. he should have said the space craft

was attracted more by the moon than by Earth

Salty is an astronaut who has a mass of 60 kg. Currently she is conducting experiments in a permanent space station that i orbiting earth at an altitude equal to earths radius. What is sally's mass as measured in the space station?

60 kg

Earth exerts a gravitational force of 7000 N on one of the communication satellites. What force does the satellite exert on Earth?

7000 N

If you double the radius of a sphere, its volume increases by what factor?

8

Two spacecraft in out space attract each other with a force of 20 N. What would the attractive force be if they were 1/2 as far apart?

80 N

Al the astronaut has a mass of 90 kg and a weight of 900 N when he is standing on Earth's surface. What is his mass when he is in space station orbiting Earth with a radius of three Earth radiii?

90 kg

The gravitational constant G in the law of universal gravitation

All of the above: Leads to a determination of the mass of earth, is believed to have the same value throughout space, is believed to be constant with time

Mercury orbits the sun about once every 80 days. When mercury is observes to keep the same side facing the sun at all times. If mercury has oceans, how much time would elapse between its high tides?

There would be no tides

If we imagine launching an apple into a circular orbit about Earth and ignore the effects of air resistance, we know that the apple will experience

a centripetal force due to gravity

Which of the following fores are exerted on a satellite that is in orbit around earth?

an attractive gravitational force directed toward the center of earth

On the surface of a certain planet, the gravitational field strength has numerical value 5.2. This means that

an object mass 1 kg will experience a gravitational force of 5.2 newtons

On the surface of a certain planet, there is one unit of gravitational force exerted on every 0.4 units of mass. Suppose that an object on the surface of this planet has a mass M. The gravitation force exerted on this object is

M/0.4

Which of the following celestial bodies has the greatest influence on Earth's tides?

Moon

Which force drives the planets along their orbits?

No force is needed to drive them along their orbits

Does the moon orbit the sun?

Yes, but it also orbits the earth

A 320 kg satellite experiences a gravitational force of 800 N. What is the radius of the satellites orbit? The earths radius is 6,400km

12,800km

Given that the acceleration due to gravity on Mars is 3.7 m/s², what is the gravitational field near mars surface?

3.7 N/kg down

The gravitational force between two metal sphere in outer space in 1800 N. How large would the force be if the two spheres were twice as far apart?

450 N

Jupiter rotates about its axis once every 10 hours. How much time passes between high tides in its atmosphere?

5 hours

On the surface of a certain planet, the gravitational field strength has numerical value gplanet. An object that experiences a gravitational foce of 0.7 newtons on this planet must have a mass of

0.7gplanet

What is the gravitational force between two 20 kg iron balls seperated by a distance of 0.5 m? The gravitational constant is G= 6.67' 10⁻¹¹ N - m²/kg²

1.07' 10⁻⁷N

A 600 kg geosynchronous satellite has an orbital radius of 6.6 earth radii. What gravitational force does earth exert on the satellite?

138 N

The masses of the moon and earth are 7.4' 10²² kg and 6' 10²⁴kg, respectively. Earth - moon distance is 3.8' 10⁸m. What is the size of the gravitational force between earth and the moon?The gravitational constant is G= 6.67' 10⁻¹¹ N - m²/kg²

2.05' 10²⁰N

What is the magnitude of earths gravitational field at a distance equal to twice Earths radius

2.5 N/kg

What is the acceleration due to earths gravity at a distance of one earth radius above earths surface?

2.5 m/s²

A future space traveler, lands on a planet that has the same mass as Earth but twice the radius. If they weigh 800 N on Earths surface, how much does he weigh on the planets surface?

200 N

If an astronaut is full gear has a weight of 1200 N on Earth, how much will the astronaut weigh on the moon?

200 N

An astronaut weighs 900 N hen measured on the surface of earth. How large would the force of gravity on him be if he were in an earth satellite at an altitude equal to earths radius?

225 N

Communication satellites are synchronous satellites that orbit earth each

24 hours

A child take a small plastic bucket full of water and swings the bucket over her head in a circular arc, just barely enough for the water to stay in the bucket. Unbeknownst to the child, a fish is in the middle of the water. At the top of the arc, the fish

Has a downward acceleration and feels weightless

The law of universal gravitation is written F = GM/r² . Why did we use the form F = mg when we studied projectile motion?

The second form is a good approximation to the first and much simpler to use

If earths mass were suddenly and magically reduced to half its present value, the suns gravitational force on earth would

be reduced by a factor of 2

The highest high tides and the lowest low tides occur when the moon is

full or new

In the law of universal gravitation the force

increases as the mass increases and decreases as the distance increases

The gravitational attraction of the sun for earth is

the same as that of the earth for the sun

Earth is held in its orbit by the gravitational force of the Sun. Therefore, the force that the Sun exerts on Earth is

the same as the force that Earth exerts on the Sun.