Lynn midterm

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

0 m/s2

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 is

0 m/s^2

What is the hang time of a person who can jump a vertical distance of 0.6 m?

0.3 m

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

0N

Disregarding air drag, how fast must you toss a ball straight up in order for it to take 2 seconds to return to the level from which you tossed it?

10 m/s

A 10-N block and a 1-N block lie on a horizontal frictionless table. To impart equal horizontal accelerations, we would have to push the heavier block with

10 times as much force.

A motorboat is driven across a river at 3.0 km/h at right angles to a current that is flowing at 10.0 km/h. What is the resulting speed of the motorboat?

10.4 km/h

A baseball player bats a ball with a force of 1000 N. The reaction force that the ball exerts against the bat is

1000 N

A bag of groceries that has a mass of 10 kilograms weighs about

100N

A car accelerates at 2 meters/s/s. Assuming the car starts from rest, how far will it travel in 10 s?

100m

A 1-kg mass at the Earth's surface weighs

10N

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

10N

The mass of a lamb that weights 110 N is about

11 kg

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the same direction. Jake's speed relative to the ground is

14 m/s

An airplane that flies at 100 km/h in a 100-km/h crosswind has a ground speed of

141 km/h

A crate falls from an airplane flying horizontally at an altitude of 1250 m. Neglecting air drag, how long will the crate take to strike the ground?

15.8 s

What is the average speed of a cheetah that runs 88 m in 5 seconds

18 m/s

You push with 27 N on a chest, and their is a 7 N force of friction. It accelerates at 4 m/s/s. What is the chests mass

2 m/s^2

A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is

20 km/h

When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of

20 m.

A jet on an aircraft carrier can be launched from 0 to 40 m/s in 2 seconds. What is the acceleration of the jet? (give answer with no post scripts)

20 m/s/s

Suppose a small plane can fly at 170 km/h relative to the surrounding air. Suppose also that there is a 60 km/h tailwind. How fast does the plane's shadow move across the ground?

230 km/h

An airplane whose airspeed is 295 km/h flies parallel to the direction of a wind with a speed of 40.0 km/h. What are the two possible speeds of the plane relative to the ground?

255 and 335 km/h

A 1000-kg automobile enters a freeway on-ramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 seconds. How far does the automobile travel during that time?

300 m

A karate chop delivers a blow of 3000 N to a board that breaks. The force that acts on the hand during this event is

3000 N

If a rocket initially at rest accelerates at a rate of 50 m/s2 for one minute, its speed will be

3000 m/s

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

4

Suppose that you exert 300 N horizontally on a 50-kg crate on a factory floor, where friction between the crate and the floor is 100 N. What is the acceleration of the crate?

4

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

400 N.

What is the resultant of a 3-unit vector and 4-unit vector at right angles to each other?

5 units

A person is attracted toward the center of Earth by a 500-N gravitational force. The Earth is attracted toward the person with a force of

500 N

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

60 m/s

Bronco the skydiver, whose mass is 80. kg experiences 200. N of air resistance. What is the acceleration of his fall?

7.3

An 80-km/h airplane flying against a 10-km/h head wind has a groundspeed of

70 km/h.

Which best approximates the resultant of a pair of 6-unit vectors at right angles to each other?

8 units

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

About 180 m

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?

About 50 m/s

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

All of the above

An object in mechanical equilibrium is an object

All of these (moving constant velocity, at rest, having no acceleration)

Bronco the skydiver falls toward Earth. The attraction of Earth on Bronco pulls him down. The reaction to this force is

Bronco pulling up on Earth.

A given force exerted on a large mass produces a greater acceleration than the same force exerted on a small mass.

False

A single vector can be replaced by two vectors in the x- and y-directions that are at right angles to each other. These two x and y vectors are called the resultants of the original vector

False

A unit of acceleration is meters per second.

False

As a ball falls freely, the distance it falls each second is the same.

False

Average speed is defined as the time it takes for a trip divided by the distance.

False

The acceleration of an object is inversely proportional to the net force acting on it.

False

The speed of an object dropped in air will continue to increase without limit.

False

When a car rounds a corner at a constant speed, its acceleration is zero.

False

When adding two vectors at right angles, the resultant of the vectors is the algebraic sum of the two vectors.

False

The scientist to first introduce the concept of inertia was

Galileo

A skydiver's terminal velocity will be greatest if she falls

Head first

If the net force on a cart is tripled, the cart's acceleration

Is three times as much

An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is

Larger

A ball is thrown vertically into the air. Because of air resistance, its speed when it returns to its starting level compared with its initial speed is

Less

In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the

Moon

The force exerted on the tires of a car to directly accelerate it along a road is exerted by the

Road

Two factors that greatly affect air resistance on falling objects are frontal area and

Speed

If you exert a force of 12,000 N on a 3,000 kg car and a 6,000 kg truck that are both originally at rest, what will be the resulting accelerations of the objects?

The car will accelerate 4 m/s^2 and the truck will accelerate 2 m/s^2.

A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to the ground first?

The heavy man

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that

The milk carton has inertia

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 is thrown is

The same

Drop a rock from a 5-m height and it accelerates at 10 m/s2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is about

The same amount

A rocketship is pushed forward by gases that are forced out the back of the ship.

True

The net force on an objecting falling at terminal velocity is zero.

True

The rate at which distance is covered is called speed.

True

When we discuss the motion of something, its motion is described relative to something else.

True

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is

Zero

When a falling object has reached its terminal velocity, its acceleration is

Zero

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

about 30 m/s.

A constant net force on a rail-road car produces constant

acceleration

Your friend says that the heavyweight champion of the world cannot exert a force of 50 N on a piece of tissue paper with his best punch. The tissue paper is held in midair - no wall, no tricks. You

agree that it can't be done

According to Newton's law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains

always have friction forces that oppose their motion.

Which has the greater mass?

an automobile battery

Arnold Strongman and Suzie Small each pull very hard on opposite ends of a massless rope in a tug-of-war. The greater force on the rope is exerted by

both the same, interestingly enough

You drive your car at a constant 60 km/h along the highway. You apply the brakes until the car slows to 40 km/h. If at that moment you suddenly release the brakes, the car tends to

continue moving at 40 km/h.

A bullet is dropped from the top of the Empire State Building while another bullet is fired downward from the same location. Neglecting air resistance, the acceleration of

each bullet is 9.8 meters per second per second.

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to

follow a straight-line path.

The newton is a unit of

force

A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the

force that the ball exerts on the bat

A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. The reaction to this force is the

force the glove exerts on the ball

According to Newton's third law, if you push gently on something, it will push

gently on you.

Compared with hang time on Earth, hang time on the Moon would be

greater

Forces always occur

in pairs

The speedometer of an automobile reads

instantaneous speed.

For an action force, there must be a reaction force that

is exactly equal in magnitude

Two tennis balls fall through the air from a tall building. One of them is filled with lead pellets. The ball to reach the ground first is the

lead-filled ball.

A vector is a quantity that has

magnitude and direction

A kilogram is a measure of an object's

mass

A rock is thrown vertically into the air. At the top of its path the net force on it is

mg

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

more than 100 m/s.

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same

none of the above

As a ball falls, the action force is the pull of Earth on the ball. The reaction force is the

pull of the ball's mass on the Earth

When you stand at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales will

read half your weight

Galileo's use of inclined planes allowed him to effectively

slow down the acceleration of free fall.

The attraction of a person's body toward Earth is called weight. The reaction to this force is

the person's body pulling on the Earth

A automobile and a baby carriage traveling at the same speed collide head-on. The impact force is

the same for both

A ball is thrown upwards and returns to the same location. Compared with its initial speed its speed when it returns is about

the same.

An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is

the same.

A heavy ball hangs by a string, with a second string attached to its bottom. A slow pull on the bottom string breaks the

top string

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

zero