PHYS 1070 Spring 23 All Exams

What is the cost of operating a 3.00-W electric clock for a year if the cost of electricity is $0.0900 per kW·h?

$2.37

If you push on a wall with a force of 10 Newtons, the force acting on you is

-10 Newtons

Free-Fall Ride Suppose a free-fall ride at an amusement park starts at rest and is in free fall. What is the velocity of the ride after 2.3 s? How far do people on the ride fall during the 2.3-s time period?

-23 m/s and -26 m

What is the velocity of the brick after 4.0 s in free fall? How far does the brick fall during this time?

-39 m/s and -78m

A racehorse coming out of the gate accelerates from rest to a velocity of 15.0 m/s due west in 1.80 s. What is its average acceleration? (East + and West -)

-8.33 m/s2

What is the acceleration of a car that maintains a constant velocity of 55 mph for 10.0 seconds?

0

The amount of net force required to keep a 5-kg object moving rightward with a constant velocity of 2 m/s is ____.

0 N

A ball is thrown 5m straight up. It takes 0.2 s to return back to the start position. What is the ball displacement after that time?

0 m

A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stopwatch measures the ball's trajectory time from the table to the floor to be 0.30 s. How far away from the table does the ball land? (g = 9.8 m/s2 and air resistance is negligible)

0.072 m

Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of 75.0 N, the second a force of 90.0 N, friction is 12.0 N, and the mass of the third child plus wagon is 23.0 kg. What would the acceleration?

0.13m/s2 in the direction of 2nd child push

A 80 kg astronaut floating in space throws a 5 kg rock at 5 m/sec. How fast does the astronaut move backwards?

0.3m/s

A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stopwatch measures the ball's trajectory time from the table to the floor to be 0.30 s. What is the height of the table? (g = 9.8 m/s2 and air resistance is negligible)

0.44 m

A 10-Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ____ Joules.

0.5

A 100-g toy car is propelled by a compressed spring that starts it moving. The car follows the curved track. What is the final speed of the toy car in ____ m/s if its initial speed is 2.00 m/s and it coasts up the frictionless slope, gaining 0.180 m in altitude.

0.7 m/s

A toy car is moving along with 0.40 joules of kinetic energy. If its speed is doubled, then its new kinetic energy will be ______

1.60 J.

An object is launched at a velocity of 20 m/s in a direction making an angle of 25° upward with the horizontal. What is the total flight time (between launch and touching the ground) of the object?

1.72 s

Study the diagram below and determine the acceleration of the box

1.77 m/s2

. Two objects are attracted to each other by a gravitational force F. If the distance between the objects is doubled, what is the new gravitational force between the objects in terms of F? A. 4 F B. 9 F C. 16 F D. 1/9 F E. 1/4 F

1/4 F

A 50-kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ____ meters.

10

An airplane lands with an initial velocity of 70.0 m/s and then accelerates opposite to the motion at 1.50 m/s2 for 40.0 s. What is its final velocity?

10 m/s

The distance-time graph represents the position of an object moving in a straight line. What is the speed of the object during the time interval t = 2.0 seconds to t = 4.0 seconds?

10.0 m/s

Big Bubba has a mass of 100 kg on the earth. What is Big Bubba's mass on the moon where the force of gravity is approximately 1/6-th that of Earth's?

100 kg

An airplane moves at 141 km/h toward the northeast (45 degrees). What is its component velocity in the northward direction?

100 km/h

A 6-kg can of paint is sitting on top of a 2-meter high step ladder. How much work did you do to move the can of paint to the top of the ladder? What is the potential energy of the can of paint?

118 J and 118 J

An airplane that flies at 100 km/h in a 100 km/h hurricane crosswind has a speed (relative to the ground) of?

141 km/h

Calculate the kinetic energy of a 5.2 kg object moving at 2.4 m/s.

15 J

How much force is needed to accelerate a 90 kg skier 2 m/s2?

180 N

What is the average velocity of an object mowing from start to 4s.

1m/s

4.0 kg block rests at the edge of a platform that is 20 m above level ground. The block is launched horizontally with an initial velocity of 15 m/s. The time it would take to reach the ground is most :

2.0 s

A 250-gram cart starts from rest and rolls down an inclined plane from a height of 0.541 m. Determine its speed at a height of 0.127 m above the bottom of the incline.

2.85 m/s

A person is pulling west with 35 N of force against a person pulling east with 15 N of force. What is the net force?

20 N west

The average speed of an object which moves 10 kilometers (km) in 30 minutes is _____________.

20 km/hr

Which one of the following quantities is NOT a vector?

20 m/s

A fireman stays away from a burning building and directs a stream of water from a fire hose at an angle of 30.0° above the horizontal. If the initial speed of the stream is 40.0 m/s, what is the maximum height of the water?

20.4 m

A student adds two vectors with magnitudes of 200 and 60. Which one of the following is the closest possible choice for the magnitude of the resultant?

209

A ball is kicked with an initial velocity of 16 m/s in the horizontal direction and 12 m/s in the vertical direction. At what speed does the ball hit the ground? ( the same like the intial velocity)

20m/s

Verify the ranges for the projectile's motion for an initial velocity of 50 m/s at the given initial angles = 45 degrees. (g = 9.8 m/s2)

255 m

Calculate the potential energy of a 5.2 kg object positioned 5.8 m above the ground.

296 J

If it takes one minute for an airplane to reach speed 100 m/s from start to take-off, how long is the take-off path (airplane displacement in that time)?

3 km

On takeoff, a rocket accelerates from rest at a rate of 50.0 m/s2 for exactly 1 minute. The rocket's speed after this minute of steady acceleration will be _____________ m/s.

3.00 x 103

Calculate the speed of a 5.2 kg object that possesses 26.1 J of kinetic energy.

3.2 m/s

A 150-N force at 30° above the horizontal is used to accelerate a 20-kg object across a level surface. There is 60 N of friction. Determine the acceleration.

3.5 m/s2

An object is launched at a velocity of 20 m/s in a direction making an angle of 25° upward with the horizontal. What is the maximum height reached by the object?

3.6 m

Which two angles will produce the same range? (in degrees)

30 and 60

A baseball pitcher delivers a fastball. During the throw, the speed of the ball increases from 0 to 30.0 m/s over a time of 0.100 seconds. The average acceleration of the baseball is _____________ m/s*s

300

An object is launched at a velocity of 20 m/s in a direction making an angle of 25° upward with the horizontal. What is the horizontal range (maximum x above ground) of the object?

31.3 m

How many Joules of energy are in one kilowatt-hour?

3600 kJ

An object's inertia depends on its mass.

3rd

When a teacher stands at the front of the class, the force of gravity pulls her toward the ground. The ground pushes back with an equal and opposite force. This is an example of which of Newton's Laws of Motion?

3rd

Dragsters can achieve an average acceleration of 26.0 m/s2. Suppose a dragster accelerates from rest at this rate for 5.56 s. How far does it travel in this time?

402 m

Which angle produces the greatest range?

45 degrees

How much work does a supermarket checkout attendant do on a can of soup he pushes 0.80 m horizontally with a force of 5.00 N? Express your answer in joules.

4J

An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. When released, the arrow will have a kinetic energy of ____ Joules.(Friction and resistance = 0)

50

Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building in 20.0 seconds. What power was required in this task?

50 W

A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water.

5000

^A bullet in a gun is accelerated from the firing chamber to the end of the barrel at an average rate of 6.20 × 105 m/s2 for 8.10 × 10-4 s. What is its muzzle velocity (that is, its final velocity)?

502 m/s^2

A powerful motorcycle can accelerate from rest to 26.8 m/s (100 km/h) in only 3.90 s. How far does it travel in that time?

52.3 m

Suppose a 55 kg gymnast climbs a rope. What is the tension in the rope if he climbs at a constant speed?

539 N

Determine the work done in the following situation: An elevator lifts 12 occupants up 21 floors (76.8 meters) at a constant speed. The average mass of the occupants is 62.8 kg

567189.5 J

A 1-kilogram coconut falls out of a tree from a height of 12 meters. Determine the coconut's potential and kinetic energy in its half way down. (at 6 meters below)

58.8 J and 58.8 J

Two objects are attracted to each other by a gravitational force F. If one mass is doubled and the other is tripled without changing the distance, what is the new gravitational force between the objects in terms of F?

6 F

Suppose you take a trip that covers 180 km and takes 3 hours to make. Your average speed is

60 km/h.

A Porsche 911 accelerates from rest to 27.8 m/s due North in 5.8 s. The mass of the car is 1400 kg. What is the magnitude and direction of the average net force that acts on the Porsche?

6710 N due North

An object is thrown horizontally off of a 125 m high cliff above level ground with an initial velocity of 15 m/s. If air resistance is negligible, the distance from the base of the cliff to the point where the object lands is most nearly

75 m

How much power is required to increase the kinetic energy of an object from 360 J to 1800 J in 3 minutes?

8 watt

Two people are pulling a refrigerator into a garage. One person is pulling south with 55N of force, while the other person is pulling south with 25.5 N of force. What is the net force?

80.5 N south

Which one of the following is NOT consistent with a car which is accelerating?

A car is moving at a high speed in a straight line

The law of _________________ of energy states that energy cannot be created or destroyed.

Conservation

A baseball player throws a ball horizontally. Which statement best describes the ball's motion after it is thrown? [Neglect the effect of friction.]

D) Its vertical speed increases, and its horizontal speed remains the same.

A 10-kg object slows down from 24 m/s to a final velocity of 9 m/s in 3 seconds. The magnitude of the net force acting upon the object is 80 N.

False ,net force=50N

At what point in its path is the horizontal component of the velocity (V) of a projectile the smallest?

It is the same throughout the path.

Which of the following is Not a unit for power?

Joule

Compare gravitational accelaration on Moon and Earth

Moon g smaller than Earth g

Dani and Gina are pushing on a box. Dani pushes with 250 N of force and Gina pushes with 150 N of forceWhat is the net force if they push in opposite directions

Net force = 100 N in Dani's direction

Which law states the need to wear seatbelts?

Newton's First Law

Which of Newton's Three Laws does the following statement satisfy? An object at rest tends to stay at rest and an object in motion tends to stay in motion in a straight line at a steady speed until an unbalanced force acts upon it.

Newton's First Law

Which of Newton's Three Laws does the following statement satisfy? The relationship between an object's mass (m), its acceleration (a), and the applied force F is F=ma. Acceleration and force are vectors. This law requires that the direction of the acceleration vector is in the same direction as the force vector.

Newton's Second Law

Which of Newton's three laws does the following example illustrate? If you have a hockey puck sliding along a table, it will eventually come to a stop.

Newton's Second Law

At what point is vy= 0 m/s?

Point B

When a large truck pushes a small car with a given force, the small car is applying an equal and opposite force on the truck.

True

An object is raised above the ground gaining a certain amount of potential energy. If the same object is raised twice as high it gains _____.

Twice as much potential energy.

Car A has a mass of 1000 kg and a speed of 60 km/h, and car B has a mass of 2000 kg and a speed of 30 km/h. The kinetic energy of car A is _____.

Twice that of car B

What is the path of a projectile (in the absence of friction)?

a parabola

Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters?

both require the same amount of work

If an object is moving eastward and slowing down, then the direction of its velocity vector is _____________.

eastward

A football is kicked into the air at an angle of 45 degrees with the horizontal. At the very top of the ball's path, its velocity is?

entirely horizontal

A football is kicked into the air at an angle of 45 degrees with the horizontal. At the very top of the ball's path, its acceleration is? (ignore air resistance)

entirely vertical

According to Newton's Third Law, action and reaction are

equal and in opposite directions

A fullback is running down the football field in a straight line. He starts at the 0-yard line at 0 seconds. At 1 second, he is on the 10-yard line; at 2 seconds, he is on the 20-yard line; at 3 seconds, he is on the 30-yard line; and at 4 seconds, he is on the 40-yard line. This is evidence that

he is moving at a constant speed (on average).

Renatta Oyle is again found driving her '86 Yugo down Lake Avenue, leaving the following trail of oil drops on the pavement. If her car is moving from right to left, then...

her velocity has a leftward direction and her acceleration has a leftward direction.

The tendency of a moving object to continue in a straight line or a stationary object to remain in place is called -

inertia

If car A passes car B, then car A must be _____________.

moving faster than car B, but not necessarily acceleration

The speed-time graph for a particle moving at constant speed is a straight-line _____________ to the time axis.

parallel

What is time and what is SI unit for time ?

scalar and second

Weight is best described as

the downward force exerted on an object due to gravity

As in the video "A bullet shoot vs bullet drop", the measurable times were

the same

A boat moves through the water in a river at a speed of 8 m/s relatives to the water. The boat makes a trip downstream and then makes a return trip upstream to the original starting place. Which trip takes longer?

the upstream trip

A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in a auto service station. Lifting the more massive car requires ____ work.

twice as much

Which type of quantity is characterized by both magnitude and direction?

vector

If an object is moving eastward and slowing down, then the direction of its acceleration vector is _____________.

westward