Part 3

A car's momentum is p when it is traveling with a velocity of v. If the velocity of that car doubles, what is the new momentum of the car?

2p

How do inertia and centripetal force combine to keep an object moving in circular motion?

Centripetal force acts toward the center of the circle, and inertia keeps the object moving forward.

What is the formula for inertial mass?

F=ma

In the equation for the gravitational force between two objects, which quantity must be squared?

d

Which formulas show the relationships between momentum, mass, and velocity? Check all that apply.

p = mv, m = p/v, v=p/m

A ball has a mass of 0.25 kg and is moving to the right at 1.0 m/s. It hits a ball of mass 0.15 kg that is initially at rest. After the collision, the 0.15 kg ball moves off to the right with a velocity of 0.75 m/s. What is the final velocity of the 0.25 kg ball?

0.55 m/s to the right

A 50 kg boy runs and jumps with a forward velocity of 1.5 m/s into a 125 kg stationary boat. What is the final velocity of the boy/boat system?

0.43 m/s, forward

A basketball player passes a ball to a teammate at a velocity of 6 m/s. The ball has a mass of 0.51 kg. If the original player has a mass of 59 kg and there is no net force on the system, what is the velocity of the player after releasing the ball? Let a positive velocity be in the direction of the pass.

-0.05 m/s

In a uniform circular motion map, what is always true? Check all that apply.

-Acceleration vectors point toward the center of the circle -Velocity vectors are the same length.

In a game of pool, a 0.4 kg cue ball is traveling at +0.80 m/s when it hits a slower striped ball moving at +0.38 m/s. After the collision, the striped ball moves off at +0.62 m/s. What is the magnitude of the final velocity of the cue ball? Assume all pool balls have the same mass.

0.56 m/s

A wrecking ball has a mass of 650 kg. It swings from a cable that is 21 m long. The centripetal force on the ball is 56 N. What is the tangential speed of the wrecking ball?

1.3 m/s

A train car has a mass of 10,000 kg and is moving at +3.0 m/s. It strikes an identical train car that is at rest. The train cars combine. What is the magnitude of the final velocity of the combined cars?

1.5 m/s

An object with a mass of 1.5 kg changes its velocity from +15 m/s to +22 m/s during a time interval of 3.5 seconds. What impulse was delivered to the object?

11 N • s

A baseball has a mass of 0.45 kg and is thrown with a speed of 25 m/s. What is the momentum of the baseball?

11 kg • m/s

In a lab, four balls have the same velocities but different masses. If the mass of ball B triples, its new momentum is kg • m/s .

13

A 0.25 kg baseball is in contact with a bat for 0.0075 s and exerts a force of 18,500 N. What impulse is delivered to the ball?

140 kg • M/s

A bowling ball has an initial momentum of +30 kg m/s and hits a stationary bowling pin. After the collision, the bowling ball leaves with a momentum of +13 kg • m/s. What is the magnitude of the final momentum of the bowling pin if it has a mass of 1.5 kg?

17 kg • m/s

The gravitational force between two objects is 45,000 N. What will be the gravitational force between the two objects if the distance between the objects is reduced by one-half?

180,000 N

The gravitational force between Pluto and Charon is 3.61 × 10^18 N. Pluto has a mass of 1.3 × 10^22 kg, which is only slightly greater than Charon's mass of 1.6 × 10^21 kg. How far apart are Pluto and Charon?

2.0 × 10^7 m

A baseball has a mass of 0.145 kilograms, and a bowling ball has a mass of 6.8 kilograms. What is the gravitational force between them if their centers are 0.5 m apart?

2.6 × 10^-10 N

A ball that has a mass of 0.25 kg spins in a circle at the end of a 1.6 m rope. The ball moves at a tangential speed of 12.2 m/s. What is the centripetal force acting on the ball?

23 N

A child on a spinning playground ride is 0.36 m from the center of the ride. The centripetal force on the child is 19 N. What is the mass of the child if the child has a tangential speed of 0.54 m/s?

23 kg

A remote-controlled plane has a mass of 0.386 kg and flies in a circle with a radius of 75 m. The centripetal force on the plane is 4.0 N. What is the tangential speed of the plane?

28 m/s

An empty 2,500 kg train car is headed northbound at a velocity of 5 m/s. Ahead of the first car, an empty 1,500 kg car is headed northbound on the same track at 1 m/s. The faster train bumps into the slower one, and they combine into one train. What is the velocity of the two-car train?

3.5 m/s

Momentum data about the same objects in the same closed system is shown below. What value should be in place of the X?

3.6

A large blue marble of mass 3.5 g is moving to the right with a velocity of 15 cm/s. The large marble hits a small red marble of mass 1.2 g that is moving to the right with a velocity of 3.5 cm/s. After the collision, the blue marble moves to the right with a velocity of 5.5 cm/s. What is the magnitude of the final velocity of the red marble?

31 cm/s

During a car accident, a 125 kg driver is moving at 31 m/s and in 1.5 seconds is brought to rest by an inflating air bag. What is the magnitude of the change in momentum of the driver?

3900 kg • M/s

The mass of the Sun is 1.99 × 10^30 kg. Jupiter is 7.79 × 10^8 km away from the Sun and has a mass of 1.90 × 10^27 kg. The gravitational force between the Sun and Jupiter to three significant figures is 10^23 N.

4.16

A 35-gram stainless steel ball on a track is moving at a velocity of 9 m/s. On the same track, a 75-gram stainless steel ball is moving at a velocity of a 7m/s. After colliding, the 35-gram ball moves at a velocity of -15 m/s. Assume there is no net force on the system. What is the velocity of the 75-gram ball after the collision? Round to the nearest tenth.

4.2 m/s

A boy and his skateboard have a combined mass of 65 kg. What is the speed of the boy and skateboard if they have a momentum of 275 kg • m/s?

4.2 m/s

The gravitational force between two objects is 3600 N. What will be the gravitational force between the objects if the mass of each object is reduced to one-third of its original mass?

400 N

The gravitational force between a satellite and Earth's moon is 324 N. The mass of the moon is 7.3 × 10^22 kg. If the distance from the moon to the satellite is 2.6 × 10^6 m, what is the mass of the satellite?

450 kg

The gravitational force between two objects is 2400 N. What will be the gravitational force between the objects if the mass of one object is doubled?

4800 N

The mass of Mars is 6.42 ×10^23 kg. Its moon Phobos is 9378 kilometers away from Mars and has a mass of 1.06 × 10^16 kg. What is the gravitational force between Mars and Phobos?

5.16 × 10^15 N

A 57 g tennis ball is traveling at 45 m/s to the right, when it hits a racket. The ball reverses direction and travels at 33 m/s. The ball is in contact with the racket for 0.0085 s. What is the magnitude of the force that was exerted on the ball?

520 N

Neptune has a mass that is about 17 times the mass of Earth. The distance between the Sun and Neptune is about 30.1 times the distance between the Sun and Earth. If the gravitational force between the Sun and Earth is 3.5 x 1028 N, which is closest to the force between Neptune and the Sun?

6 x 10^26 N

Julius competes in the hammer throw event. The hammer has a mass of 7.26 kg and is 1.215 m long. What is the centripetal force on the hammer when it has a tangential speed of 31.95 m/s? The answer is rounded off to the nearest whole number.

6,100 N

A probe orbiting Venus exerts a gravitational force of 2.58 × 10^3 N on Venus. Venus has a mass of 4.87 × 10^24 kg. The mass of the probe is 655 kilograms. The gravitational constant is 6.67 × 10^-11 N*m^2/kg^2. To three significant digits, the probe is _ × 10^6 m from the center of Venus.

9.08

A 0.060 kg ball hits the ground with a speed of -32 m/s. The ball is in contact with the ground for 45 milliseconds and the ground exerts a +55 N force on the ball. What is the magnitude of the velocity after it hits the ground?

9.3 m/s

The acceleration due to gravity on Jupiter is 23.1 m/s^2, which is about twice the acceleration due to gravity on Neptune. Which statement accurately compares the weight of an object on these two planets?

An object weighs about two times as much on Jupiter as on Neptune.

A student performs a lab measuring the velocities of toy cars of different masses. Which cars have the same magnitude of momentum? Check all that apply.

Car 1, Car 2

Shari uses the data in the table to predict how her weight on Venus would compare with her weight on Earth. Which is the best prediction Shari could make?

Her weight is lower on Venus because the acceleration due to gravity is lower.

Review the table detailing the mass of Jupiter's moons and their distance from the planet. Which of Jupiter's moons has the greatest gravitational force with Jupiter?

Io

How does a centripetal force cause circular motion?

It acts at a right angle to the object's motion and causes the object to constantly change direction.

What must be true of a force that causes an object to move in a circular motion?

It acts perpendicular to the velocity and is directed toward the center of the circle.

Different forces were applied to five balls, and each force was applied for the same amount of time. The data is in the table. If the force on ball A doubles while the time remains the same, what happens to the impulse?

It doubles.

How is the gravitational force related to the distance between two objects?

It is inversely proportional to the square of the distance.

Two grocery carts have the same initial total momentum. The two carts collide, and now cart B has a greater final velocity. Which best describes the final total momentum of both the carts compared to the initial total momentum?

It is the same if no external forces are added.

An object is in circular motion. How will the object behave if the centripetal force is removed?

It would move in a line tangent to the circular path.

Without inertia, how would an object that is experiencing a centripetal force behave?

It would move in a line toward the circle's center.

What are possible formulas for impulse? Check all that apply.

J = F(delta)t, J = m(delta)v, J = (delta)p

When working with the Universal Law of Gravity formula, what are appropriate units of measure? Hint: Consider metric measures of mass.

Kilograms, Meter

In an elastic collision, _ energy is conserved.

Kinetic

Two carts, one of mass 2m and one of mass m, approach each other with the same speed, v. When the carts collide, they hook together. Assume that positive momentum is to the right. Which graph best represents the momentum of both carts over time, before and after the collision?

Lines combine below the X axis with blue on top and red on bottom

Two identical carts travel at the same speed toward each other, and then a collision occurs. The graphs show the momentum of each cart as a function of time, both before and after the collision. Which graph shows a perfectly inelastic collision?

Lines combine on the x-axis with only red on top and only blue on bottom.

Which factors affect the force of gravity? Select all that apply. Hints: Recall the formula used to calculate the force of gravity.

Mass of both objects, Distance between the centers of mass

Fill in the blank to complete the following statement: Newton is credited with discovering the Universal Laws of Gravitation. Hint: Know that this scientist is also responsible for discovering the link between planetary orbit and gravitational force.

Newton

What is an effect of gravity on objects on the surface of Earth? Check all that apply.

Objects accelerate at a rate of 9.8 m/s each second, Objects "fall" toward the center of Earth.

Lucia wants to change the motion map shown so that it shows uniform circular motion. What change should Lucia make?

She should change the lengths of the vectors that point toward the center so that each is the same length.

The gravitational force between two objects is 2000 N. The mass of each object is reduced to one-third of its original mass.How must the distance between the objects change to keep the gravitational force between them 2000 N?

The distance must be one-third the original distance.

A rubber bullet of mass m is fired from a rifle into a stationary block of 25 m. The bullet remains in the block and both the bullet and the block move off with a common velocity. Assume this is an inelastic collision in a closed system. Which best describes the final momentum of the bullet/block?

The final momentum of the bullet/block is equal to the initial momentum of the bullet.

Students perform an experiment in which they drop two eggs with equal mass from a balcony. In the first trial, the egg hits the ground and breaks. In the second trial, the egg hits a foam cushion and does not break or bounce. What conclusions about impulse can the students make?

The impulse was the same in both experiments because the egg came to a stop.

Which of these factors plays no direct part in determining the magnitude of the force of gravity on the objects? Hint: The sun will expand into a red giant one day - but its gravity will change very little.

The radius of the objects, The distance between the surfaces of the objects

For a movie stunt, an empty truck with a mass of 2000 kg goes 10 m/s and runs into a stopped car of mass 1000 kg. The truck then keeps moving and pushes the car along with it. If there are no other forces acting on this system, which best describes the results of the collision?

The speed of the combined vehicles is less than the initial speed of the truck.

The image shows a model of the gravitational field around Earth. Which best describes the model?

The strength of the field increases as you get closer to Earth, as shown by the smaller spaces between the circles.

Two blocks are initially at rest with a compressed spring between them. When the spring is released, the 2m block moves to the left and the m block moves to the right. This represents an inelastic collision in a closed system. What best describes the blocks after the spring is released?

The total momentum is zero.

In a lab, two identical lab carts (m = 1.0 kg) travel toward each other, each with a speed of 2 m/s. The cars collide, and one cart moves to the right with a speed of 3 m/s and the other moves left with a speed of 2 m/s. What best explains the results of the experiment?

This experiment did not occur in a closed system.

An object is represented by the dot on the motion map. Which object is most likely represented by the motion map?

V,W,Y

Scientists are making plans to put a probe in orbit around Earth. They want the probe to enter the orbit shown below. Which arrow shows the direction that the probe should be moving in order for it to enter the orbit?

X

Suchita makes a table to identify the variables used in the equations for centripetal force. What quantities belong in cells X and Y?

X: radius Y: tangential speed

An object is represented by the dot on the motion map. Which object is most likely represented by the motion map?

a ball twirled on a string that just broke

Four identical lab carts each have a mass of 200 kg. Different masses are added to the carts and the velocities are measured. All carts move to the right. Which cart has the greatest momentum?

cart A

Which changes would result in a decrease in the gravitational force between two objects? Check all that apply.

decreasing the mass of both objects, decreasing the mass of one of the objects, increasing the distance between the objects

What type of relationship exists between momentum and mass?

direct

The gravitational force between two objects is _ proportional to the product of the masses of the objects.

directly

Johanna makes the table below to organize her notes about centripetal forces. Which type of force should she place in the cell marked X?

gravity

A perfectly _ collision occurs when two objects stick together and kinetic energy is lost.

inelastic

A girl is standing still in the middle of a baseball field. The girl catches the baseball and begins to move in the same direction as the thrown ball. What type of collision is being described?

inelastic, since the girl moves in the same direction as the thrown ball

As a truck rounds a curve, a box in the bed of the truck slides to the side farthest from the center of the curve. This movement of the box is a result of .

inertia

What is the SI unit for momentum?

kg • m/s

What are possible units for impulse? Check all that apply.

kg • m/s , N • s

Two bumper cars move toward each other. The cars hit and bounce off of each other. The momentum before the collision will be equal to the after.

momentum

What is the direction of the centripetal force when applied to an object?

perpendicular to an object's motion

Which equation best describes the law of conservation of momentum?

pi = pf

The universal law of gravitation states that the force of attraction between two objects depends on which quantities?

the masses of the objects and the distance between them

What best describes an impulse acting on an object?

the product of an object's mass and its change in velocity

A centripetal force causes circular motion because it accelerates an object

toward the center of a circle, which changes the direction of motion but not the speed.

Students are completing a lab in which they let a lab cart roll down a ramp. The students record the mass of the cart, the height of the ramp, and the velocity at the bottom of the ramp. The students then calculate the momentum of the cart at the bottom of the ramp. Which trials cart has the greatest momentum at the bottom of the ramp?

trial 3, because this trial has a large mass and a large velocity

Which are examples of perfectly inelastic collisions? Check all that apply.

two train cars coupling together, rain sticking to a window, a plane landing on an aircraft carrier

Which equation is used to calculate the weight of an object on a planet?

w = mg

What is the downward pull on an object due to gravity?

weight