Physics midterm1

A 5kg shark swimming F a speed of 1 m/s swallows an absent-minded 1kg fish swimming toward if at 4 m/s. The speed of the shark after this meal is

C. 1/6 m/s

A 5kg fish swimming at a Speed of 1 m/s swallows an absent-minded 1kg fish at rest. The speed of the larger fish after this lunch is

C. 5/6 m/s

A jack system will increase the potential energy of a heavy load by 1000J with a work input of 2000J . The efficiency of the jack system is

C. 50%

When a women stands at rest with both feet on a scale, it reads 500 N. When she gently lifts one foot, the scale reads

C. 500 N

Suppose a miracle car has a 100% efficient engine and burns fuel that has a 40 megajoules per liter energy content. If the air drag and overall frictional forces on this car traveling at highway speeds total 1000N, what is the overall limit in distance per liter it could be driven on the highway?

B. 40 km

A man weighing 800 N stands at rest on 2 bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

B. 400 N

A 1kg rock that weighs 9.8 N is thrown straight upward at 20m/s. Neglecting air resistance, the net force that acts on it when it is half way to the top of its path is

B. 9.8 N

A ball is thrown upward and then falls the same distance back to Earth. Neglecting air resistance, its total time in the air is

B. About 10 seconds

A rifle of mass 2 kg is suspended by strings. The rifle fired a bullet of mass .01 kg at a speed of 200 m/s. The recoil velocity of the rifle is aboht

D. 1 m/s

A car moves 4 times as fast as another identical car. Compared to the slower car, the faster car has

D. 16 times the KE

A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the net force exerted on the car?

D. 2000 N

A car accelerates from rest for 5 seconds until it reaches a speed of 20m/s. What is the car's acceleration in meter per second per second?

D. 4

A TV set is pushed a distance of 2 m with a force of 20 N. How much work is done on the set?

D. 40 J

A 10kg block with an initial velocity of 10m/s slides 10 m across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about

D. 50 N

The force of an apple hitting the ground depends upon

D. All of these

An astronaut on another planet drops a 1kg rock from rest. The astronaut notices that the rock falls 2 meters straight down in one second. On this planet, how much does the rock weigh?

B. 4 N

If a car increases its velocity from 0 to 60 km/hr in 10 seconds, its acceleration is

B. 6km/h/s

If you are driving at 20ms/ and slam on your brakes and skid at .5g to a full stop, the skidding time in seconds is

B. about 4

A 10N falling object encounters 10N of air resistance. The net force on the object is

A. 0N

A 10 kg brick and a 1kg book are dropped in a vacuum. The force of gravity on the 10kg brick is

B. 10 times as much

Compared to falling On a Stone floor, a wine glass may not break when it falls on a carpeted floor because the

C. Stopping time is longer on the carpet

A sack of potatoes weighing 200 N falls from an airplane. As the velocity of the fall increases, air resistance also increases. When air resistance equals 200N, the sack's acceleration in meters per second per second is

A. 0

A 1kg chunk of putting moving at 1 m/s collides with and sticks to a 5kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of

B. 1 Kg m/s

It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the floor?

B. 10 N

An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about

B. 10m/s

On a sunny day about 500W of solar power are received by each other the 4 solar cells on the roof of a solar powered automobile. If the solar cells were 100% efficient, they would deliver

B. 2.7 hp

A car traveling at 22m/s comes to an abrupt halt in 0.1 second when it hits a tree. What is the deceleration in meters per second per second of the car?

B. 220

Both a 50kg sack is lifted 2 meters from the ground and a 25kg sack is lifted 4 meters at the same time. The power expended in raising the 50kg sack is

C. the same

An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be

C. twice as much

A falling skydiver of mass 100kg experiences 500N of air resistance. The acceleration of the skydiver is

D. 0.5 kg

At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed should be about

D. 60m/s

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second is approximately

A. 0

An apples weighs 1N. When held at rest above your head, the net force on the apple is

A. 0N

A 10kg block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meter per second per second is

A. 1

If a projectile is fired straight up at a speed of 10m/s, the time it takes to reach the top of the path is about

A. 1 second

A machine puts out 100W of power for every 1000 Watts put into it. The efficiency of the machine is

A. 10%

A 4 kg ball has a momentum of 12kg m/s. What is the ball's speed?

A. 3 m/s

At one instant a heavy object in air is moving upward at 50 meters per second. One second later its speed in meters per second is approximately

A. 40m/s

An airplane flies at 100km/hr in still air. If it flies into a 10km/hr headwind, its groundspeed is?

A. 90km/hr

A pot falls from a ledge and hits the ground 45 m below. The speed with which it hits the ground is

A. About 30m/s

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds?

A. About 50m/s

A ball is projected into the air with 100J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is

A. Less than 100J

A ball thrown straight upward takes 10 seconds to go up and return to the ground. Because of air resistance, The time taken for the ball just to go up is

A. Less than 5 s

A golf ball moving forward with 1 unit of momentum strikes and bounces backward off a heavy bowling ball that is initially at rest and free to move. The bowling ball is set in motion with a momentum of

B. More than 1 unif

An apple at rest weighs 1 N. The net force on the apple when it is in free fall is

C. 1 N

A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both move with a combined momentum of

C. 1 unit

A 1kg chunk of putty moving At 1 m/s collides with and sticks to a 5kg bowling ball that is initially at rest on a frictionless surface. The speed of the putty thereafter is

C. 1/6 m/s

Consider massive gliders that slide friction-free along a horizontal air track. Glider A has a mass of 1kg. Speed of 1m/s, and collides with glider B that has a mass of 5kg and is at rest. If they stick upon collision, their speed after collision will be

C. 1/6 m/s

A tow truck exerts a force of 3000 N on a car, accelerating it at 2 meters per second per second. What is the mass of the car?

C. 1500 N

A jumbo jet has a mass of 100,000kg. The thrust for each of its 4 engines is 50,000N. What is the jet's acceleration in meters per second per second when taking off?

C. 2

A 2500N pile-driver ram falls 10m and drives a post 0.1m into the ground. The average impact force on the ram is

C. 250,000 N

Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration in meters per second per second?

C. 4.0

The change in momentum, in kg m/s, that occurs when a 1 kg ball traveling at 4 m/s strikes a wall and bounced back at 2 m/s is

C. 6

A block is dragged without acceleration in a straight-line path across a level surface by a force of 6 N. What is the force of friction between the block and the surface?

C. 6 N

A 10N falling object encounters 4N of air resistance. The net force on the object is

C. 6N

A 10 N force is pulling up on the ring of a spring scale that weights 2 N. If an 8 N mass is attached to the bottom hook of the scale, the scale reading would be

C. 8 N

The vertical height attained by a basketball player who achieves a hang time of a full 1s is

C. About 1.2 m

It takes about 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?

C. About 180 m

The human body can, under certain conditions, withstand an acceleration of 10g. What net force would produce this acceleration of a 50kg person?

C. About 5000 N

An object lifted 10 meters gains 200 J of potential energy. If the same object is lifted 20 meters, its potential energy gain is

C. Twice as much

A 1000kg car and a 2000kg car are hoisted the same distance. Raising the more massive car requires

C. Twice as much work

A car's engine is 20% efficient. When cruising the car encounters an average retarding force of 1000N. If the energy content of the gasoline is 40 megajoules per liter, how many kilometers per liter does the car get?

D. 8

A 2kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?

D. 80 J

Compared to the force that brings a small car to a stop, the force required to bring a heavy truck to stop

D. Is impossible to determine without additional information

Twelve seconds after starting from rest, an object falling freely will have a speed of

D. No more than 100m/s

A pulley system raises a 1000N load 2 meters with 100N of input force. The efficiency of the system is

D. Not enough information to answer

Consider a hydraulic press. When the input piston is depressed 20 cm, the output piston is raised 1 cm. On the same press, an input force of 1N can lift a load of

E. All of the above are correct

A large heavy truck and a small baby carriage roll down a hill. Neglecting friction, at the bottom of the hill, the baby carriage will have a greater

E. None of these

A sandbag is motionless In Outer space. A second sandbag with 3 times the mass moving at 12 m/s collides with it. They stick together and move at a speed of

E. None of these