PHY181 QUIZ2

What is surface gravity? What's the value of surface gravity on the Moon?

Surface gravity is the acceleration a mass undergoes at the surface of a celestial object (e.g., an asteroid, planet, or star). The value of surface gravity on the moon is 1.625 m/s^2

If the force of gravity exerted on the Sun by the Earth is the same as the force exerted by the Earth on the Sun, why does the Earth orbit the Sun, and not the other way around? a. the combined gravitational forces of all the planets keeps the sun at the center of the solar system b. the earth is less massive, and is accelerated more by the gravitational force and moves faster c. planets, by definition, orbit the sun, and not the other way around d. they each orbit around the geometric center of the system e. none of these choices is correct

The Earth is less massive, and is accelerated more by the gravitational force and moves faster

If you double the distance between two bodies, the force of gravity between them would a. decrease by one fourth b. double c. decrease by one half d. become four times as strong

decrease by one fourth

If the distance between two masses is tripled, the gravitational force between them is a. decreased by a factor of 9 b. increased by a factor of 3 c. decreased by a factor of 3 d. increased by a factor

decreased by a factor of 9.

If your mass is 60 kilograms on Earth, what is it on the Moon? a. 0 kilograms, because the Moon has no gravity b. 360 kilograms, because the Moon is a spherical object c. 60 kilograms, because mass does not depend on gravity d. 120 kilograms, because the Moon's gravity is greater than Earth's

60 kilograms, because mass does not depend on gravity

What is Newton's first law of motion? a. Force equals mass times acceleration, F=ma b. A body continues in a state of rest of uniform motion in a straight line unless made to change that state by forces acting on it c. every mass exerts a force on any other mass that is proportional to the product of the masses divided by the square of the distance between them d. when two bodies interact, they create equal and opposite forces on each other

A body continues in a state of rest or uniform motion in a straight line unless made to change that state by forces acting on it.

A delivery truck and a car collide. Which vehicle experiences the greater force? a. the truck b. the car c. both the car and the truck experience the same force d. We need to know the speed of the truck and the car to find the answer. e. We need to know the mass of the truck and the car to find the answer

Both the car and the truck experience the same force

What is escape velocity? How is it related to the mass and radius of a celestial object?

Escape velocity is a critical speed needed to overcome a celestial object's gravitational force and escape into space. It is related to the mass and radius of a celestial object because those dimensions are needed to determine if the mass will escape.

What is Newton's Second law of motion? a. Every mass exerts a force on any other mass that is proportional to the product of the masses divided by the square of the distance between them. b. A body continues in a state of rest or uniform motion in a straight line unless made to change that state by forces acting on it. c. Force equals mass times acceleration, F = ma. d. When two bodies interact, they create equal and opposite forces on each other.

Force equals mass times acceleration, F = ma.

What property summarizes a body's tendency to stay in the state of rest or motion? a. volume b. temperature c. pressure d. acceleration e. inertia

Inertia

How does mass differ from weight?

Mass is the amount of matter an object contains. This differs from weight because weight is a force related to gravity which changes from place to place whereas mass remains the same.

When a bus makes a sudden stop the passengers lurch forward as a consequence of ______ law. a. Newton's first b. Newton's third c. Kepler's Third

Newton's first

State Newton's Law of Gravity. Write down the corresponding equation.

Newton's law of universal gravity states that everything attracts everything else: the gravitational force between two particles of Mass (M and m) are separated by a distance 'd' and is proportional to the product of the masses are inversely proportional to the square of the distances. Fg=G(M*m)/d^2)

State Newton's third law and give an example to explain.

Newton's third law states that when two objects interact, they create equal and opposite forces on each other. An example of this is when two people bump into each other, their equal and opposite forces will make them stumble backwards from each other

What is meant by inertia?

The idea of inertia was established by Galileo and states that a body at rest tends to stay at rest, and a body in motion tends to stay in motion.

An object is traveling in a circular path with constant speed. Do you think the motion of the object is uniform motion? If not, what should be the direction of the acceleration and force acting on the object?

The motion of this object is not uniform motion. If an object moves in a circular path, there is a net (unbalanced) force working on it called centripetal force.

Suppose that the Sun started shrinking in size, without losing any mass. What would be the effect of the Sun's change on the orbits of the planets? a. The orbits would become larger. b. The planets would escape. c. The orbits would not be affected d. The orbits would become smaller in size

The orbits would not be affected

A parachutist jumps out of an airplane and opens her parachute. She then floats downward at a constant rate. Why is she not accelerating? a. the parachute provides an upward force to balance gravity, so the net force is zero b. the parachutist exerts a gravitational pull on the Earth that is equal to its pull on her c. she is accelerating, but gravity's pull is weak at high altitudes d. the parachute has very little mass, so its inertia is negligible e. as she falls, she is weightless and therefore cannot accelerate

The parachute provides an upward force to balance gravity, so the net force is zero

Write down all seven fundamental physical quantities and the corresponding SI units.

The seven physical quantities are: - length (meter) -mass (kilogram) - time (second) - electric current (ampere) - thermodynamic temperature (Kelvin) - amount of substance (mole) -luminous intensity (candela)

What is uniform motion?

Uniform motion is when the speed and direction of an object remain constant.

How are mass and weight different? a.Weight is a measure of how much gravity pulls an object; mass is how much matter the object has b. Weight is the amount of matter an object contains; mass is the type of matter an object is made of. c. There is no difference; they are the same d. Mass is the amount of matter an object contains; weight is how much mass an object contains.

Weight is a measure of how much gravity pulls an object; mass is how much matter the object has.

The Moon is gravitationally attracted to the Earth. Is the Earth gravitationally attracted to the Moon? a. yes, but the force of attraction is less b. no. the moon has no gravity c. yes, and the force of attraction is the same d. yes, but the force of attraction is greater

Yes, and the force of attraction is the same.

If you are lucky enough to get a chance to visit different planets of our Solar System, which of the following statements will be true? a. both your weight and mass will change b. your mass will change, but your weight will remain the same c. your weight will change, but your mass will remain the same d. both your weight and mass will remain the same

Your weight will change, but your mass will remain the same

Which statement is true about Newton's First law of motion? a. a body in motion stays in motion unless a force is applied to it. b. a body at rest stays at rest unless a force is applied to it. c. a body in motion has the tendency to stop eventually d. a body at rest stays at rest unless a force is applied to it and a body in motion has the tendency to come to a stop eventually e. a body at rest stays at rest unless a force is applied to it and a body in motion stays in motion unless a force is applied to it

a body at rest stays at rest unless a force is applied to it and a body in motion stays in motion unless a force is applied to it

A 200-kg spacecraft is launched to the Moon. After it has landed on the Moon, its weight is ________. a. zero b. 200 kg c. about 1/6 its weight at Earth d. the answer depends on which side of the Moon the spacecraft landed on

about 1/6 its weight at Earth

If the net force acting on an object doubles, then the ______ doubles as well. a. acceleration b. velocity c. mass d. speed

acceleration

Which of the following objects (A-D) are accelerating? A. an object at rest, B. an object in motion in a straight line at a constant speed, C. an object in motion in a straight line with increasing speed, D. an object moving in a circle at constant speed. a. an object at rest only b. all but an object at rest c. an object in motion in a straight line with increasing speed only d. an object in motion in a straight line with increasing speed and an object moving in a circle at constant speed

an object in motion in a straight line with increasing speed and an object moving in a circle at constant speed.

The escape velocity from the Moon is 2.4 km/s. If an astronaut hits a golf ball such that it just reaches this speed, the ball will ________. a. either orbit the Moon or escape its gravitational pull, depending on the direction the ball is hit b. move away from the Moon, but return some time later c. continue moving away from the Moon, never to return d. follow a very elliptical orbit around the Moon

continue moving away from the Moon, never to return

The gravitational force exerted by the Sun on the Earth is ________ the gravitational force exerted by the Earth on the Sun. a. unrelated to b. equal to c. greater than d. less than

equal to

The speed an object needs to move away from the gravitational pull of the Earth is called a. rotational velocity b. random velocity c. escape velocity d. orbital velocity

escape velocity

What does escape velocity measure? a. how far away an object needs to be to escape a planet's gravity b. how fast an object needs to go to escape hostile space aliens c. the gravitational attraction at a planet's surface d. how fast an object needs to go to escape a planet's gravity

how fast an object needs to go to escape a planet's gravity

If an object's mass (M) is doubled, the gravitational force between it and other object will be a. increased by a factor of 2 b. decreased by a factor of 2 c. decreased by a factor of 4 d. increased by a factor of 4

increased by a factor of 2

What do we call the tendency of a body at rest to remain at rest or a body in motion to remain in motion? a. inertia b. the "action-reaction" law c. gravity d. the tendency of a person to stay in bed in the morning

inertia

While riding a bicycle, if you stop pedaling you will still continue to move forward due to a. inertia b. gravity c. pressure d. acceleration

inertia

Newton's modification of Kepler's Third law allows astronomers to determine the ________ of celestial objects. a. period b. acceleration c. distance d. mass

mass

The recoil experienced when firing a shotgun is a consequence of ________ law. a. newton's third b. kepler's third c newton's first

newton's third

A delivery truck and a car collide. Which vehicle experiences the greater acceleration? a. the truck b. the car c. Both the car and the truck experience the same acceleration. d. We need to know the speed of the truck and the car to find the answer. e. We need to know the mass of the truck and the car to find the answer.

the car

In your office, you have a rolling chair and a rolling filing cabinet. The chair weighs 10 pounds, and the filing cabinet weighs 50 pounds (it's partly full). If you push both of them away with about the same strength a. the cabinet will accelerate about 25 times as much as the chair. b. the chair will accelerate about 25 times as much as the cabinet. c. the cabinet will accelerate about 5 times as much as the chair d. the chair will accelerate about 5 times as much as the cabinet. e. both will accelerate about the same.

the chair will accelerate about 5 times as much as the cabinet.

What does surface gravity measure? a. the attraction between the surfaces of two massive objects b. how fast an object needs to go escape a planet's gravity c. the tendency of a planet's surface to collapse under gravity d. the gravitational acceleration at a planet's or stars stars surface

the gravitational acceleration at a planet's or star's surface

After tying a string to a rock, you twirl the rock around above your head. If the string were to break, what path would the rock follow? a. the rock will complete the circle before falling down b. the rock will fly upward c. the rock will go in a straight line before falling down d. the rock will fall down immediately

the rock will go in a straight line before falling down

When an astronaut experiences weightlessness in space, their mass is a. the same as on the Earth b. becoming lesser and lesser as s/he is going higher c. double that on the Earth d. zero

the same as on the Earth

Consider a large truck and a small car driving up a straight, steep hill. The truck is moving at 60 miles per hour and the car at 30 miles per hour. Assuming that the speeds are constant, which of the two vehicles experiences a larger net force? a. the car b. the truck c. the same: zero net force

the same: zero net force

A car is moving down a straight, steep hill. By applying the brake, the driver is able to keep the speed of the car constant. Which of following statements is true in this situation? a. the net acceleration is negative b. there is no net force on the car c. there is a net force on the car

there is no net force on the car

If you see a body in space that is not moving in a straight line at constant speed, what can you say about it? a. there must be a net force acting on it b. it is not subject to any outside forces c. it must be an artificial satellite d. none of these choices are correct

there must be a net force acting on it

If a newly discovered planet has four times the mass of the Earth, but it still has the same surface gravity as Earth, how big must this new planet be? a. one fourth of the size of Earth b. four times as large as Earth c. half the size of Earth d. the same size as Earth e. twice as large as Earth

twice as large as Earth