PHYS 101 Unit 2

A push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with

10 times as much force.

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

10 times as much.

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

500 N

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 in meters per second per second is

0

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

0 N

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

1 second

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

2

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

20 km/h

An object, at rest near the surface of a distant planet, starts to fall freely . If the acceleration there is twice that of the earth, its speed one second later would be

20 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

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

40 m/s

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

One half second after starting from rest, a freely-falling object will have a speed of about

5 m/s

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

6 km/h/s

If a car accelerates from rest at 2 meters per second per second, its speed 3 seconds later will be about

6 m/s

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

A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle that undergoes the greatest change in velocity will be the

Volkswagen

A bag of groceries has a mass of 10 kilograms and a weight of

about 100 N.

If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be

greater than the second before.

An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration

halves

An object following a straight-line path at constant speed

has zero acceleration

Your weight is

the gravitational attraction force between you and the Earth.

A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass?

the one on the moon.

A feather and a coin will have equal accelerations when falling in a vacuum because

the ratio of each object's weight to its mass is the same.

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

10 N

A 1-kg ball is thrown at 10 m/s straight upward. Neglecting air resistance, the net force that acts on the stone when it is halfway to the top of its path is about

10 N.

An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. After 5 seconds, the object will have a speed of

100 m/s

A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed of 400 m/s . It can be stopped by applying a constant force of 20 N for

800 seconds.

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. How far below the level from which it was thrown is the rock 2 seconds later?

9.8m

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

If the mass of an object does not change, a constant net force on the object produces constant

acceleration.

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.

If an object moves with constant acceleration, its velocity must

change the same amount each second.

Your car is coasting on level ground at 60 km/h and you apply the brakes until the car slows to 40 km/h. If you suddenly release the brakes now, the car tends to

continue moving at 40 km/h

Suppose a particle is being accelerated through space by a 10-N force. Suddenly the particle encounters a second force of 10 N in the opposite direction from the first force. The particle with both forces acting on it

continues at the speed it had when it encountered the second 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 large and a small person wish to parachute at equal terminal velocities. The larger person will have to

get a larger parachute.

If one object has twice as much mass as another object, it also has twice as much

inertia.

Wherever the is an action force, there must be a reaction force which

is exactly equal in magnitude.

A lightweight feather slides off a table and falls through the air until it reaches the floor. During the time of its fall,.its acceleration

is sometimes zero.

A bullet is dropped into a river from a very high bridge. At the same time, another bullet is fired from a gun, straight down towards the water. Neglecting air resistance, the acceleration just before striking the water

is the same for each bullet.

A skydiver steps from a helicopter and falls for a few seconds until he reaches his terminal velocity. Thereafter, until he opens his parachute, his acceleration

is zero.

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

moon.

A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is

more.

A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is

the same for both.

A horse exerts 500 N of force on a heavy wagon. The wagon pulls back on the horse with an equal force. The wagon still accelerates because

there is still an unbalanced force on the wagon

Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the greater speed will be

they will both hit with the same speed.