Multiple Choice Final

Starting from rest, an object rolls freely down an incline that is 5 meters long in 1 second. The acceleration of the object is approximately

10 m/s/s

The terminal speed for a person parachuting (with the chute open) is about

15 km/h

Starting from rest, the distance a freely falling object will fall in 5 seconds is about

125 m

A 15-N force and a 45-N force act on an object in opposite directions. What is the net force on the object?

30 N

The reason a car moves at constant speed along the road is because the friction between the tires and the road causes a forward reaction force to act on the car.

False

Which of the following would exert the most pressure on the ground?

a woman standing in high-heel shoes

It takes 5 s for a stone to fall to the bottom of a mineshaft. How deep is the shaft?

about 125 m

An object has a constant mass. A constant force on the object can produce constant

acceleration

In the absence of air resistance, objects fall at a constant

acceleration

A ball thrown in the air will never go as far as physics ideally would predict because

air friction slows the ball

If an object is pushed or pulled and it remains at rest, there must be a force keeping it at rest that is larger than the pushing or pulling force

always false

The product of mass and acceleration, ma, is a force

always false

A ball will go the farthest if thrown almost horizontally

false

A force applied by, say a hand, still acts on an object after the object leaves the hand

false

A steel ball and a wood ball of the same size are released together from the top of a tower. In the absence of air resistance, they both would reach the ground at the same time. The reason for this is that the force on each ball is the same.

false

All forces are mediated through contact; forces cannot be exerted between two things if they are not in contact

false

All motion, including constant-velocity motion, are sustained by a "force of motion"

false

An object in motion stays in motion because of the inertia force acting on it.

false

Excluding the force due to air pressure, there is only one force acting on a book lying at rest on a table top.

false

If an object is pushed of pulled and it remains at rest because of its inertia (its mass is too great)

false

If velocity is zero, then acceleration must be zero too

false

If you slide a hockey puck across a frictionless ice rink, there must be a horizontal force on it to keep it in motion

false

In order to make a cart move forward, a horse must pull harder on the cart than the cart pulls on the horse.

false

Inertia is just another way of saying weight.

false

Speed is proportional to force (ex. the higher the speed, the higher the force)

false

The higher the velocity, the higher the acceleration

false

Accelerations are produced by

forces

The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that the steel ball

has a larger force also has a larger mass

An object following a straight-line path a constant speed

has zero acceleration

The momentum change of an object is equal to the

impulse acting on it

In order to increase the final momentum of a gold ball, we could

increase the force acting on it, follow through when hitting the ball, increase the time of contact with the ball, swing as hard as possible

How does acceleration of an object change in relation to its mass? It is

inversely proportional

The acceleration produced by a net force on an object is

inversely proportional to the mass of the object, directly proportional to the magnitude of the net force, in the same direction as the net force

A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it

is not acted on by any horizontal forces

If the momentum of an object changes and its mass remains constant,

its accelerating/decelerating, there is a force acting on it, and its velocity is changing

The hang time (time one's feet are off the ground in a jump) for most athletes is

less than 1 second

A ball is thrown upwards and caught when it come back down. In the presence of air resistance, the speed with which it is caught

less than the speed it had when thrown upwards

A small economy car (low mass) and a limousine (high mass) are pushed from rest across a parking lot, equal distances with equal forces. The car that receives the grater impulse is the

limosine

An object maintains its state of motion because it has

mass

Inertia is a measure of an object's

mass

An airplane flying into a head wind loses ground speed, and an airplane flying with he wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed is

more

If the force of gravity suddenly stopped acting on the planets, the would

move in straight lines tangent to their orbits

When in orbit, a satellite such as the space shuttle is

simple a projectile

The most effective egg drop uses which of the following?

small terminal velocity and increased time of impact

Change in velocity can be obtained from

the area under an acceleration-time graph

Which one of the following statements correctly describes the motion of an object depicted by the position vs. time graph below?

the object has constant velocity

An object weighs 30 N on earth. A second object weights 30 N on the moon. Which has the greater mass?

the one on the moon

A force of 3 N accelerates a mass of 3 kg at the rate of 1 m/s/s. The acceleration of a mass of 6 kg acted upon by a force of 6 N is

the same

Aunt Minnie throws a rock downward, and air resistance is negligible. Compared to a rock that is dropped, the acceleration of the rock after it its thrown is

the same

Compared to its mass on Earth, the mass of a 10-kg object on the moon is

the same

A bullet fired horizontally hits the ground in 1.0 second. If it had been fired with a much higher speed in the same direction, it would have hit the ground (neglecting the Earth's curvature and air resistance) in

the same time 1s

Two balls that are exactly the same size and shape. One ball is made out of aluminum and has a mass of 0.5 kg. The other one is made out of uranium (its covered with lead so that no radiation leaks out) and has a mass of a 6.0 kg. If they are released at the same instant from the same height of 20 m they will reach the ground at

the same time with the same speeds

Galileo found that a ball rolling down one incline plane would roll how far up another inclined plane?

to nearly its original height

An astronaut has the same mass on earth as in space

true

Even though a car is slowing down, it is still accelerating, in the most general definition of accelerating

true

The vector sum of all the forces (or the net force) acting on an object is called the resultant.

true

On the position vs. time graph, the slope of the line represents the

velocity

As an object falls freely in a vacum, its

velocity increases

A body falls freely from rest near the surface of the earth. The distance the object falls in 4 seconds is

-80 m

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

0 N

An apple weighs 1 N. The net force on the apple when it is in free-fell is

1 N

The vertical height attained by a basketball player who achieves a hang time of a full one second is about

1.2 m

Suppose the force of friction on a sliding object is 10 N. The force needed to maintain a constant velocity is

10 N

A 747 jumbo jet has a mass of 30,00 kg. The trust for each of four engines is 15,000 N. What is the jet's acceleration when taking off?

2 m/s/s

If a projectile is fired straight up at a speed of 20 m/s, the time it takes to reach the top of its path is about

2 s

An apple falls from a tree and hits the ground 20 m below. It hits the ground with a speed of about

20 m/s

What is the maximum resultant possible when adding a 16-N force to an 8-N force?

24 N

A girl whose weight is 500 N hangs from the middle of a bar supported by two vertical strands of rope. What is the tension in each strand?

250 N

If a projectile is fired straight up at a speed of 15 m/s, the total time to return to its starting point is about

3 seconds

Two forces are applied on a soccer ball simultaneously. One player kicks the ball with a force of 20 N North. The other player kicks the ball with a force of 30 N West. What is the magnitude of the net force applied on the soccer ball?

36 N

A car accelerates from rest at 2 meters per second per second. What is its speed 2 second after the car starts moving?

4 m/s

A radar transmitter sends out a pulse that is reflected from the moon's surface. The signal return 3.0 s after it is sent (ie. it goes there and back). What is the best estimate of the moon's distance from the earth if light travels at 3.0x10 to the eighth m/s?

4.5x10 to the eighth m

If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 40 m/s/s, then its speed reading would increase each second by

40 m/s

A jumbo jet cruises at a constant velocity when the total thrust of the engine on the jet is 40,000 N. How much air resistance acts on the jet?

40,000 N

Mr. Vining see Mr. Hill under his balcony. Mr. Vining drops a water balloon that falls freely for 3 second before striking Mr. Hill on the head and getting him soaking wet. How far did the balloon travel before striking Mr. Hill?

45 m

A ball is thrown 32 meters straight upward and then falls the same distance back to earth. Neglecting air resistance, its total time in the air is about

5 s

A ball is hurled into the air at an angle of 10 degrees and lands on a target that is at the same level as that where the ball started. The ball will also land on the target if it is thrown at an angle of

80 degrees

Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle

continues at the speed it had when it encountered the second force

The are under a velocity-time graph represents

displacement

In order to find the components of a vector, you should

draw the vector with correct magnitude and orientation, measure the sides of the rectangle, a and draw a rectangle so that the vector is the diagonal.