Gravity

If an object is dropped from a tall building and hits the ground 3.0 s later, what is the velocity of the object when it hits the ground? (Remember that the velocity is downward) v= _____ m/s -21 m/s -29 m/s -431 m/s -860 m/s

-29

An object is dropped on Earth from a height of 15 m. How long did it take for the object to reach the ground? 1.2 seconds 1.5 seconds 1.8 seconds 3.0 seconds

1.8

If an object is thrown in an upward direction from the top of a building 1.6 x 102 ft. high at an initial velocity of 21.82 mi/h, what is its final velocity when it hits the ground? (Disregard wind resistance. Round answer to nearest whole number and do not reflect negative direction in your answer.)

110

An object is dropped on Earth from a height of 15 m. What is the magnitude of the velocity of the object just as it hits the ground? 0 m/s 4.4 m/s 9.8 m/s 17 m/s

17

If the 50.0 kg boy were in a spacecraft 5R from the center of the earth, what would his weight be? (Use the 50.0 kg boy for significant figures) 100 N 98 N 20. N 19.6 N

19.6 N

If an object is thrown up at an initial velocity of 9.8 m/s, how long will it take to fall back to the ground?

2.0

If an object is dropped from a tall building and hits the ground 3.0 s. later, what is the magnitude of the object's displacement in 1.0 s.; in 2.0 s.?

4.9 20

If an object is dropped from a tall building and hits the ground 3.0 s later, how tall is the building?

44

Calculate the force at sea level that a boy of mass 50 kg exerts on a chair in which he is sitting. 50 kg up 50 kg down 490 N up 490 N down

490 N down

Objects on the moon's surface have an acceleration due to gravity one-sixth that on the earth's. What would the 50 kg boy weigh on the moon?

82 N

Rank the following forces from strongest to weakest force fields. Strong Force > Electromagnetic Force > Gravitational Force > Weak Force Electromagnetic Force > Strong Force> Weak Force > Gravitational Force Gravitational Force > Electromagnetic Force > Weak Force > Strong Force Strong Force > Electromagnetic Force > Weak Force > Gravitational Force

Strong Force > Electromagnetic Force > Weak Force > Gravitational Force

Considering , will F ever equal zero? yes no not enough information

no

According to Newton's Law of gravity, which of the following is inversely related to the square of the distance from earth? mass weight gravitational Constant distance

weight

Since , what happens to F as d gets larger? F increases F decreases rapidly F stays the same F is not related to d

F decreases rapidly

When in orbit, astronauts experience weightlessness. What is this caused by? The astronauts have no mass in space. Gravitational forces do not occur in space. The astronauts experience no contact (normal) forces with their surroundings. Astronauts are too far away from the Earth to feel its gravitational pull.

The astronauts experience no contact (normal) forces with their surroundings.

Consider a girl that has a mass of 55.0 kg and is standing on the floor, how much supporting force does the floor have? at least 55 kg up at least 55 kg down at least 539 N up at least 539 N down

at least 539 N up

Why doesn't an object thrown in an upward direction fall the same distance in each time interval as it descends toward Earth? because it is falling toward the earth because it is heavier than the air it is falling through because it is accelerating none of the above

because it is accelerating