PhysicsFinal (Multiple Choice)

Suppose our sun had 4 times its present mass but the earth orbited it at the same distance as it presently does. What would be the length of the year on the earth under those conditions?

1/2 as long as the present year

A 2.0-kg ball moving eastward at 3.0 m/s suddenly collides with and sticks to a 4.0-kg ball moving northward at 2.0 m/s. What is the magnitude of the momentum of this system just after the collision?

10 kg * m/s

A race car traveling at a constant speed of 50 m/s drives around a circular track that is 500 m in diameter. What is the magnitude of the acceleration of the car?

10 m/s^2

If a net force accelerates a 4.5-kg tool at 40 m/s2, what acceleration would that same net force give to an 18-kg tool?

10 m/s^2

You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it

moves along a straight-line path in its original direction.

Two planets have the same surface gravity, but planet B has twice the mass of planet A. If planet A has radius r, what is the radius of planet B?

r√2

You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is

slowing down

Two friends are standing on opposite ends of a canoe that is initially at rest with respect to a frictionless lake. The person in the front throws a very massive ball toward the back, and the person in the back catches it. After the ball is caught, the canoe is

stationary

The reason an astronaut in an earth satellite feels weightless is that

the astronaut is falling

When a 45-kg person steps on a scale in an elevator, the scale reads a steady 410 N. Which of the following statements must be true? (There could be more than one correct choice.)

the elevator is accelerating downward at a constant rate.

Two objects of different mass have equal, non zero kinetic energies. Which object has the greater magnitude momentum?

the heavier object

An object is moving with constant velocity. Which of the following best describes the force(s) acting on the object?

the net force acting on the object is zero

In a collision between two unequal masses, which mass receives a greater magnitude impulse?

they receive equal impulses

During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away. This gun also had a very long barrel. What was the reason for using a long barrel in these guns?

to allow the force of the expanding gases from the gunpowder to act for a longer time

Swimmers at a water park have a choice of two frictionless water slides, as shown in the figure. Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the bottom of slide 1 compare with v2, the speed of a swimmer reaching the end of slide 2?

v1=v2

Which one has larger kinetic energy: a 500-kg object moving at 40 m/s or a 1000-kg object moving at 20 m/s?

500-kg object

In a police ballistics test, a 2.00-g bullet suddenly hits and becomes embedded in a 5.00-kg wood block which is hanging from a 1.20-m long string. This causes the block to swing through an arc of 3.50°. What was the speed of the bullet just before it hit the block?

524 m/s

A 1500-kg car traveling at 90 km/h toward the east suddenly collides with a 3000-kg car traveling at 60 km/h toward the south. The two cars stick together after the collision. What is the direction of motion of the cars after collision?

53.1° S of E

The curved section of a horizontal highway is a circular unbanked arc of radius 740 m. If the coefficient of static friction between this roadway and typical tires is 0.40, what would be the maximum safe driving speed for this horizontal curved section of highway?

54 m/s

A golf ball of mass 0.050 kg is at rest on the tee. Just after being struck, it has a velocity of 102 m/s. If the club and ball were in contact for 0.81 ms what is the average force exerted on the ball by the club

6.3 KN

A 1200 kg ore cart is rolling at 10.8 m/s across a flat friction free surface. A crane suddenly drops 858 kg of ore vertically into the cart. How fast does the cart move just after being loaded with the ore?

6.30 m/s

An astronaut drops a marble on the surface of the airless Planet Z-49 and observes that it takes 1.02 s for the marble to fall 2.00 m starting from rest. She also knows that the radius of Z-49 is 3.39 × 106 m. From this information, what will she determine for the mass of Z-49? (G = 6.67 × 10-11 N • m2/kg2)

6.62 × 10^23 kg.

An astronaut weighs 99 N on the Moon, where the acceleration of gravity is 1.62 m/s2. How much does she weigh on Earth?

600 N

A truck is using a hook to tow a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is 6000 N, then the force exerted by the car on the truck is

6000 N

A 1200 kg car is pulling 500 kg trailer along level ground. Friction of the road on the trailer is negligible. The car accelerates with an acceleration of 1.3 m/s^2. What is the force exerted by the car on the trailer

650 N

If I weigh 741 N on Earth at a place where g = 9.80 m/s2 and 5320 N on the surface of another planet, what is the acceleration due to gravity on that planet?

70.4 m/s^2

A person who normally weighs 700 N is riding in a rather swift elevator that is moving at a constant speed of 9.8 m/s. If this person is standing on a bathroom scale inside the elevator, what would the scale read?

700 N

The coefficient of static and kinetic frictions between a 3.0-kg box and a desk are 0.40 and 0.30, respectively. What is the force of friction on the box when a 15 N horizontal force is applied to the box?

8.8 N

A child does 350 J of work while pulling a box from the ground up to his tree house at a steady speed with a light rope. The tree house is 4.0 m above the ground. What is the mass of the box?

8.9 kg

A jet plane flying 600 m/s experiences an acceleration of 4.0 g when pulling out of a circular dive. What is the radius of curvature of the circular part of the path in which the plane is flying?

9200 m

How much work would a child do while pulling a 12 kg wagon a distance of 4.3 m with a 22 N force?

95 J

Three objects are moving along a straight line as shown in the figure. Taking the positive direction to be to the right, what is the total momentum of this system?

- 14.0 kg * m/s

A 35 N bucket of water is lifted vertically 3.0 m and then returned to its original position. How much work did gravity do on the bucket during this process?

0 J

A person carries a 25.0-N rock through the path shown in the figure, starting at point A and ending at point B. The total time from A to B is 1.50 min. How much work did gravity do on the rock between A and B?

0 J

You carry a 7.0 kg bag of groceries 1.2 m above the ground at constant speed across a 2.7 m room. How much work do you do on the bag in the process?

0 J

Two air track carts move along an air track towards each other. Cart A has a mass of 450 g and moves toward the right with a speed of 0.850 m/s. Cart B has a mass of 300 g and moves toward the left with a speed of 1.12 m/s. What is the total momentum of the two-cart system?

0.047 kg • m/s toward the right

An object slides on a level surface in the +x direction.? It slows and comes to a stop with a constant acceleration of 2.4 m/s2. What is the coefficient of kinetic friction between the object and the floor?

0.24

Two ice skaters suddenly push off against one another starting from a stationary position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire relative to the ice?

0.28 m/s

A 0.140-kg baseball is dropped and reaches a speed of 1.20 m/s just before it hits the ground and bounces. It rebounds with an upward velocity of 1.00 m/s. What is the change of the ball's momentum during the bounce?

0.308 kg • m/s upwards

It requires 0.30 KJ of work to fully drive a stake into the ground. If the average resistive force on the stake by the ground is 828 N how long is the stake?

0.36 m

The radius of the earth is R. At what distance above the earth's surface will the acceleration of gravity be 4.9 m/s2?

0.41 R

A 45.0-kg person steps on a scale in an elevator. The scale reads 460 N. What is the magnitude of the acceleration of the elevator?

0.422 m/s^2

A 0.14-kg baseball is dropped from rest from a height of 2.0 m above the ground. What is the magnitude of its momentum just before it hits the ground if we neglect air resistance?

0.88 kg *m/s

If Earth had twice its present mass but it orbited at the same distance from the sun as it does now, its orbital period would be

1 year

A 20-g bead is attached to a light 120 cm-long string as shown in the figure. If the angle α is measured to be 18°, what is the speed of the mass?

1.1 m/s

At their closest approach, Venus and Earth are 4.20 × 1010 m apart. The mass of Venus is 4.87 × 1024 kg, the mass of Earth is 5.97 × 1024 kg, and G = 6.67 × 10-11 N • m2/kg2. What is the magnitude of the gravitational force exerted by Venus on Earth at that point?

1.10 x 10^18 N

A 250-kg motorcycle goes around an unbanked turn of radius 13.7 m at a steady 96.5 km/h. What is the magnitude of the net force on the motorcycle?

1.31 x 10^4 N

Suppose NASA wants a satellite to revolve around Earth 5 times a day. What should be the radius of its orbit if we neglect the presence of the Moon? (G = 6.67 × 10-11 N m2/kg2, Mearth = 5.97 × 1024 kg)

1.44 x 10^7 m

A 100 g ball falls from a window that is 12 m above ground level and experiences no significant air resistance as it falls. What is its momentum when it strikes the ground?

1.5 kg * m/s

In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges?

1.50 m/s

A force produces power P by doing work W in a time T. What power will be produced by a force that does six times as much work in half as much time?

12 P

A certain aircraft has a mass of 300,000 kg. At a certain instant during its landing, its speed is 27.0 m/s. If the braking force is a constant 445,000 N, what is the speed of the airplane 10.0 s later?

12.2

A policeman investigating an accident measures the skid marks left by a car. He determines that the distance between the point that the driver slammed on the brakes and the point where the car came to a stop was 28.0 m. From a reference manual he determines that the coefficient of kinetic friction between the tires and the road under the prevailing conditions was 0.300. How fast was the car going when the driver applied the brakes? (This car was not equipped with anti-lock brakes.)

12.8 m/s

A car heading north suddenly collides at an intersection with a truck of the same mass heading east. If they lock together and travel at 28 m/s at 15 degrees north of east just after the collision, how fast was the car initially traveling

14 m/s

A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at 13.0 m/s in the same direction. If the second car has a mass of 790 kg and a speed of 15.1 m/s right after the collision, what is the velocity of the first car after this sudden collision?

14.0 m/s

A 55 kg box rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.30. A horizontal 140-N force is applied to the box. what is the friction on the box

160 N

How many joules of energy are used by a 1.0-hp motor that runs for 1.0 hour? (1 hp = 746 W)

2.7 MJ

A 1200-kg cannon suddenly fires a 100-kg cannonball at 35.5 m/s. What is the recoil speed of the cannon? Assume that frictional forces are negligible and the cannon is fired horizontally.

2.9 m/s

Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer space. They suddenly push each other apart. How far has the heavier astronaut moved when the lighter astronaut has moved 12 m? 9.0 m 12 m 7.0 m 21 m

21 m

A 50 kg box is being pushed along a horizontal surface. The coefficient of static friction between the box and the ground is 0.65, and the coefficient of kinetic friction is 0.35. What horizontal force must be exerted on the box for it to accelerate at 1.2 m/s^2

230 N

A 0.50-kg toy is attached to the end of a 1.0-m very light string. The toy is whirled in a horizontal circular path on a frictionless tabletop. If the maximum tension that the string can withstand without breaking is 350 N. What is the maximum speed the mass can have without breaking the string?

26 m/s

You are driving at 30.0 m/s on a freeway curve of radius 25.0 m. What is the magnitude of your acceleration?

26.0 m/s^2

A tiger is running in a straight line. If we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor?

4

A traveler pulls on a suitcase strap at an angle 36 degrees above the horizontal. If 555 J of work are done b y the strap while moving the suitcase a horizontal distance of 15 m what is the tension in the strap

46 N

Two planets have the same surface gravity, but planet B has twice the radius of planet A. If planet A has mass m, what is the mass of planet B?

4m

A net force of 125 N is applied to a certain object. As a result, the object accelerates with an acceleration of 24.0 m/s2. The mass of the object is

5.21 kg

Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?

50 mph to 60 mph

A heavy dart and a light dart are launched vertically by identical ideal springs. Both springs were initially compressed by the same amount. There is no significant air resistance. Which of the following statements about these darts are correct? (There could be more than one correct choice.)

At the maximum height, both darts have the same gravitational potential energy, The light dart goes higher than the heavy dart.

Satellite A has twice the mass of satellite B, and moves at the same orbital distance from Earth as satellite B. Compare the speeds of the two satellites.

The speed of B is equal to the speed of A.

Three cars (car L, car M, and car N) are moving with the same speed and slam on their brakes. The most massive car is car L, and the least massive is car N. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, for which car is the amount of work done by friction in stopping it the greatest?

Car L

A satellite is in orbit around the earth. Which one feels the greater force?

Earth and the satellite feel exactly the same force

Two small balls, A and B, attract each other gravitationally with a force of magnitude F. If we now double both masses and the separation of the balls, what will now be the magnitude of the attractive force on each one?

F

Two small objects, with masses m and M, are originally a distance r apart, and the magnitude of the gravitational force on each one is F. The masses are changed to 2m and 2M, and the distance is changed to 4r. What is the magnitude of the new gravitational force?

F/4

In order to lift a bucket of concrete, you must pull up harder on the bucket than the bucket pulls down on you.

False

The Moon is accelerated toward the earth, so it is gradually getting closer to the earth.

False

You pull on a crate with a rope. If the crate moves, the rope's pull on the crate must have been larger than the crate's pull on the rope, but if the crate does not move, both of these pulls must have been equal.

False

A small car and a large SUV are at a stoplight. The car has a mass equal to half that of the SUV, and the SUV can produce a maximum accelerating force equal to twice that of the car. When the light turns green, both drivers push their accelerators to the floor at the same time. Which vehicle pulls ahead of the other vehicle after a few seconds?

It is a tie

A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth's gravity?

It is never beyond the pill of earths gravity

You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

It would have skidded 4 times farther.

A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in the figure, which shows a bird's-eye view (as seen from above). Which path (A-E) will the rock follow?

Path B

Let the orbital radius of a planet be R and let the orbital period of the planet be T. What quantity is constant for all planets orbiting the sun, assuming circular orbits?

T2/R3

The same net force is applied to two different objects. The second object has twice the mass of the first object. Compare the acceleration of the two objects.

The acceleration of object 1 is twice the acceleration of object 2.

When a 45-kg person steps on a scale in an elevator, the scale reads a steady 480 N. Which of the following statements must be true? (There could be more than one correct choice.)

The elevator is accelerating upward at a constant rate.

A large truck collides head-on with a small car. The car is severely damaged as a result of the collision. According to Newton's third law, how do the forces acting between the truck and car compare during the collision?

The force on the truck is equal to the force on the car.

Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce back from the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greater impact force on your car?

The force would be the same in both cases

A very elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of the following statements about the bounce are correct? (There could be more than one correct choice.)

The magnitude of the ball's momentum was the same just before and just after the bounce.

A constant net force acts on an object. Which of the following best describes the object's motion?

The object is moving with a constant acceleration.

An object of mass m rests on a flat table. The earth pulls on this object with a force of magnitude mg. What is the reaction force to this pull?

The object pulling upward on the earth with force mg

An object is moving in the absence of a net force. Which of the following best describes the object's motion?

The object will continue to move with a constant velocity.

Which of the following statements are true? Select all correct responses. Choose all that apply.

The total momentum of any number of particles is equal to the vector sum of the momenta of the individual particles, The vector sum of forces acting on a particle equals the rate of change of momentum of the particle with respect to time, The total momentum of an isolated system is constant.

If the force on an object is in the negative direction, the work it does on the object must be

The work could be either positive or negative, depending on the direction the object moves.

Three cars (car F, car G, and car H) are moving with the same speed and slam on their brakes. The most massive car is car F, and the least massive is car H. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, which car travels the longest distance to skid to a stop?

They all travel the same distance in stopping

While flying horizontally in an airplane, you notice that a string dangling from the overhead luggage compartment hangs at rest at 15° away from the vertical toward the front of the plane. Using this observation, you can conclude that the airplane is

accelerating backwards

A bucket is being lowered by a very light rope with a constant downward velocity. The tension in the rope must be

equal to the weight of the bucket

In an inelastic collision involving an isolated system, the final total momentum is

exactly the same as the initial momentum

A small car collides with a large truck. Is the acceleration experienced by the car greater than, less than, or equal to the acceleration experienced by the truck? Best Explanation: ?

greater than Both vehicles experience the same magnitude of force, therefore the lightweight car experiences the greater acceleration.

An elevator suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be

greater than the weight of the elevator

If a quantity you calculated had units of kg • m/s, what type of quantity could it be?

impulse, momentum

Halley's Comet is in a highly elliptical orbit around the sun. Therefore the orbital speed of Halley's Comet, while traveling around the sun,

increases as it nears the Sun.

If a satellite moves with constant speed in a perfectly circular orbit around the earth, what is the direction of the acceleration of the satellite?

inward toward the earth

When an object moves in uniform circular motion, the direction of its acceleration is

is directed toward the center of its circular path

Which of the following quantities are units of momentum? / Which of the following quantities are units of impulse?

kg * m/s, N * S

A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read?

less than 700 N