Science Midterm Study Guide

A rock climber dislodges a stone while climbing a mountain. The stone falls straight down, taking exactly 3.5 seconds to hit the ground. Ignoring air resistance, how fast was the stone traveling when it hit the ground? Remember to include the correct unit. Formula: v = g x t v = velocity of the object when it hits the ground. g = gravitational constant, 9.8 meters per second squared t = time in seconds

34.3 m/s

If you put a 20 N book on the top shelf of a 2 m high bookshelf, what gravitational potential energy do you give the book? • 10 J. • 18 J. • 22 J. • 40 J.

40 J.

Let's say a pin being juggled by a juggler has a potential energy of 10 J and kinetic energy of 400 J. What is the pin's mechanical energy? • 40 J. • 390 J. • 410 J. • 4,000 J.

410 J.

In an action film, the hero is running along the top of a train toward engine (the front of the train.) The train is going 40 m/s. He's chasing a villain at a rate of 3 m/s. A bystander on the ground wonders how fast the hero is moving. To the bystander on the ground, the hero's total velocity (resultant velocity) is: • 37 m/s forward. • 40 m/s forward. • 43 m/s forward. • 3 m/s forward.

43 m/s forward.

A friend is helping you to rearrange your bedroom furniture. You exert 25 N of force to push the foot-end of the bed forward while your friend exerts 20 N of force pulling the head-end of the bed in the same direction. The net force being used to move the bed is: • 45 N forward • 20 N forward. • 5 N forward. • 15 N forward.

45 N forward

Two forces act on an object. One force has a magnitude of 10 N and is directed toward the north. The other force has a magnitude of 5 N directed toward the south. The object experiences a net force of: • 5 N south. • 15 N north. • 5 N north. • 15 N south.

5 N north.

A hot air balloon floats low in the sky. You see it pass your house and 10 seconds later pass a building you know to be 50 m away. You estimate the speed of the balloon to be: • 0.2 m/s • 5 m/s • 10 m/s • 50 m/s

5 m/s

What force is necessary to accelerate a 1,250 kg car at a rate of 40 m/s2 ? (Formula: F = ma, where F = force, m = mass, and a = acceleration) • 31.25 N • 40.0 N • 1,290 N • 50,000 N

50,000 N

You are training to run the 100 m race at a track and field meet. You time yourself and find you can run it in 13 seconds. How fast are you able to run it? • 1 m/s • 7.7 m/s • 1.13 m/s • 1.30 m/s

7.7 m/s

You are in Chicago, IL. You decide to head south to Austin, TX. In one hour, you travel 80 km. Your velocity is: • 80:1 • 80 km • 80 km/h • 80 km/h south

80 km/h south

What is the kinetic energy of a car with a mass of 4000 kg traveling at 20 m/s? • 80,000 J • 800,000 J • 1,600,000 J • 160,000,000 J

800,000 J

All objects accelerate toward the Earth at what rate?

9.8 m/s/s

Which of the following will have the greatest air resistance? • A crumpled up sheet of paper. • A flat, non-crumpled sheet of paper. • An apple. • An acorn.

A flat, non-crumpled sheet of paper.

A. State Newton's 1st Law (all parts). B. Describe how motions or actions in in your favorite sport follow Newton's first law.

A. An object at rest stays at rest and an object in motion remains in motion at a constant speed in a straight line unless acted on by an unbalanced force. B. In golf, the ball remains motionless on the tee unless being hit by the club, showing its resistance to change in motion, also known as inertia.

A. State Newton's 3rd Law. B. Give an example of a "force pair" from your favorite sport.

A. Whenever an object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. B. When I am holding the ball in basketball, the force of my hands on the ball is the action force, and the force of the ball on my hands is the reaction force.

A force: • is expressed in newtons. • can cause an object to speed up, slow down, or change direction. • is a push or a pull. • All of the above.

All of the above.

According to Newton's second law, acceleration of an object • decreases as the mass of the object increases. • increases as the force on the object increases. • is in the same direction as the force on the object. • All of the above.

All of the above.

After a motor pulls the roller coaster cars up the first hill, what keeps the cars moving down and up and around the following hills, turns, and loops? • Gravity • Inertia • Acceleration • All of the above.

All of the above.

When a swimmer swims through water, • the action force could be the swimmer's hands and feet pushing on the water. • the reaction force could be the water pushing back on the hands and feet. • the reaction force is what moves the swimmer forward. • All of the above.

All of the above.

Which of the following is a conversion from chemical energy to thermal energy? • Food is digested and used to regulate body temperature. • Charcoal is burned in a barbecue pit. • Coal is burned to boil water. • All of the above.

All of the above.

Newton's 1st Law states: (p 145)

An object at rest stays at rest and an object in motion stays in motion at a constant speed and in a straight line unless acted upon by an unbalanced force.

As you jump on a trampoline, your kinetic energy of movement is at its max at what point? a. At the top of the jump, just before you begin to fall back down. b. At the bottom of the jump, just before you touch the trampoline. c. Halfway between the top of the jump and the bottom of the jump. d. At the bottom of the jump when you are at the deepest part of the stretched trampoline.

At the bottom of the jump, just before you touch the trampoline.

What kind of friction is air resistance?

Fluid friction

What does all objects accelerating toward the Earth at 9.8 m/s/s mean?

For every second that an object falls, the object's downward velocity increases by 9.8m/s

What 2 motions combine to create an "orbit"?

Forward motion and free fall toward Earth because of the gravitational pull.

Define "free fall" and name 2 places that "free fall" can occur:

Free fall occurs only when gravity is pulling on an object, and no other forces are acting on it. • In a vacuum • A space ship orbiting earth

What does the amount of air resistance acting on an object depend upon?

It depends upon the size and shape of the object

Because work and energy are so closely related, they are both expressed in • Newtons. • Newton-kgs. • Calories. • Joules.

Joules.

Gravitational force depends on the ____ of the objects and the distance between them. • Weight • Mass • Speed • Force

Mass

If fossil fuels are nonrenewable, why do we use them for energy? • They do not produce pollution. • They provide a large amount of thermal energy per unit of mass. • They do not cause acid rain. • All of the above.

They provide a large amount of thermal energy per unit of mass.

If three different balls were dropped at the same time from the top of a six-story building, which would hit the ground first? (Assume there is no air resistance.) • a golf ball. • A softball. • A bowling ball. • They would all hit at the same time.

They would all hit at the same time.

A soccer ball is sitting on the field. A player runs up to it and kicks it, and it flies through the air. Are the forces on the kicked soccer ball balanced or unbalanced? How do you know? Explain.

Unbalanced, because the ball went from not moving to moving. It is flying through the air. When the ball was kicked, no opposing force occurred on the other side of the ball.

An acorn falls from a tree and hits the ground after 3.5 seconds. What is its velocity when it hits the ground? Show your work.

V=gt V= 9.8 m/s/s x 3.5s V= 34.3 m/s

________ is a measure of the gravitational force of an object.

Weight

You are walking quickly on a moving sidewalk in an airport. The sidewalk is moving forward at 1 m/s. You are walking in the same direction at 1 m/s. You look like you are moving at 2 m/s compared to: • another moving person on the moving sidewalk. • another non-moving person on the moving sidewalk. • a person sitting in a chair in the airport. • the sun.

a person sitting in a chair in the airport.

All objects fall with the same _______.

acceleration (9.8 m/s/s)

Objects fall to the ground at the same rate because

acceleration due to gravity is the same for all objects

An object is accelerating when: • its speed changes. • its direction changes. • its speed and direction changes. • all of the above.

all of the above.

Coal, petroleum, and natural gas are all examples of • fossil fuels. • super-concentrated forms of the sun's energy. • non-renewable resources. • all of the above.

all of the above.

Mechanical energy can be • all potential energy. • all kinetic energy. • part potential and part kinetic energy. • all of the above.

all of the above.

When rolling downhill, a roller coaster's potential energy is converted into • kinetic energy. • thermal energy. • sound energy. • all of the above.

all of the above.

Venus and Earth have nearly the same mass. Therefore, the gravitational pull from the sun is approximately: • the same for both even though Venus is closer to the sun. • greater for Venus because it is closer to the sun. • less for Venus because it is closer to the sun. • greater for EArth because it is farther from the sun.

greater for Venus because it is closer to the sun.

Your class and another class have a tug-of-war contest. For your class to win, your class must: • create a balanced force with the other class. • have a greater force in the direction opposite the other class. • have a greater force in the same direction as the other class. • create a net force of zero with the other class.

have a greater force in the direction opposite the other class.

An object that has kinetic energy must be • at rest. • lifted above the Earth's surface. • in motion. • None of the above.

in motion.

7. As an object falls, the upward force of air resistance continues to ________ until it exactly matches the downward force of gravity. When this happens, the net force is ________ and the object stops accelerating. The object then falls at a ________ velocity, which is called ________.

increase zero constant terminal velocity

Parachutes slow skydivers to a safer terminal velocity because parachutes • increase air resistance. • decrease air resistance. • increase gravitational pull. • decrease gravitational pull.

increase air resistance.

If Earth's mass doubled, your weight would: • increase because gravity increases. • decrease because gravity increases. • increase because gravity decreases. • Not change because you are still on Earth.

increase because gravity increases.

Gravitational force between 2 objects _____ as mass increases. (increases or decreases)

increases

All objects accelerate toward the Earth at a rate of 9.8 m/s/s. This means that for every second that an object falls, its downward velocity • increases by 9.8 m/s. • decreases by 9.8 m/s. • stays at 9.8 m/s • None of the above.

increases by 9.8 m/s.

An object in motion tends to stay in motion because of its tendency to resist any change in motion. This tendency is called:

inertia

Newton's first law is sometimes called the law of ______

inertia

If a car driver suddenly makes a sharp turn, the passenger slides to the side of the car because of • free fall. • inertia. • gravity. • friction.

inertia.

Newton's third law of motion states that if a force is exerted on an object, another force occurs that • is equal in size and opposite in direction. • is equal in size and in the same direction. • is equal in speed and opposite in direction. • is equal in speed and in the same direction.

is equal in size and opposite in direction.

Galileo proved that if there is no air resistance, the rate at which an object falls (how fast it falls) • increases with an increase in mass. • decreases with an increase in mass. • is not affected by the mass. • increases with a decrease in mass.

is not affected by the mass.

A property of a moving object that depends on the object's mass and velocity is called:

momentum

A _________ is determined by combining forces.

net force

Which of the following is NOT a renewable resource? • wind energy • nuclear energy • solar energy • geothermal energy

nuclear energy

Because the moon's gravitational force is one-sixth that of Earth's, an astronaut's weight on the moon is: • the same as on Earth because gravitational force affects mass, not weight. • six times that on Earth. • one-sixth that on Earth. • one-third that on Earth because Earth's gravity is also pulling on the astronaut.

one-sixth that on Earth.

Coal was formed from the remains of ____ that were in swamps millions of years ago. • plants. • animals. • rocks. • dinosaurs.

plants.

If an object's mechanical energy remains constant and its kinetic energy increases, its • potential energy remains the same. • potential energy increases. • potential energy decreases. • total potential energy plus kinetic energy increases.

potential energy decreases.

Suppose you are jumping on a trampoline. At the top of your jump, your • mechanical energy is zero. • potential energy is at a maximum. • kinetic energy and potential energy are equal. • potential energy is zero.

potential energy is at a maximum.

As a pendulum swings downward, its • potential energy is maximum. • potential energy is converted into kinetic energy. • kinetic energy is maximum. • kinetic energy is converted into potential energy.

potential energy is converted into kinetic energy.

Balanced forces applied to an object: • produce a negative net force. • produce a net force of zero. • cause an object at rest to start moving. • change the direction of a moving object.

produce a net force of zero.

The curved path traveled by a thrown baseball is known as • centripetal force. • orbit. • projectile motion.

projectile motion.

When observing an object in motion compared to an object that appears to stay in place, the object that appears to stay in place is called a _________.

reference point

The amount of air resistance acting on an object depends on the object's • mass and weight. • density and mass. • size and shape. • None of the above.

size and shape.

Total distance divided by total time gives an object's average ________.

speed

When a skydiver is falling before pulling his parachute, he will reach a point at which the upward force of air resistance will exactly match the downward force of gravity. When this happens, he will stop accelerating and fall at a constant velocity. This is called:

terminal velocity

During photosynthesis, plants: • combine carbon dioxide with oxygen. • use light energy to produce new substances with chemical energy. • convert thermal energy into kinetic energy. • break down food molecules to release energy.

use light energy to produce new substances with chemical energy.

The speed of an object in a particular direction is an object's _______.

velocity

Kinetic energy depends on • mass and volume. • velocity and weight. • weight and height. • velocity and mass.

velocity and mass.

Gravitational potential energy depends on • mass and speed. • weight and height. • mass and weight. • height and distance.

weight and height.

When gravitational force changes: • weight changes. • mass changes. • weight stays the same. • direction changes.

weight changes.

According to Newton's first law of motion, a moving object that is not acted on by an unbalanced force • will eventually come to a stop. • will remain in motion. • will transfer its energy to another object. • will accelerate in the absence of friction.

will remain in motion.

Write the formula for the velocity of falling objects: (acceleration due to gravity problems. See "Math Break".)

∆v=g x t

As you climb higher in a tree, you are gaining in • kinetic energy. • gravitational potential energy. • light energy. • chemical energy.

gravitational potential energy.

__________ is the force of attraction between objects that is due to their masses.

gravity

At what point does a roller coaster have the greatest potential energy? • The top of the biggest hill. • The bottom of the biggest hill. • The top of the smallest hill. • The bottom of the smallest hill.

The top of the biggest hill.

A force that opposes motion between two surfaces that are touching is: • gravity. • velocity. • friction. • acceleration.

friction

Voyager 2 was launched into space on Aug. 20, 1977 to study the outer solar system. Today it is still travelling in the same direction at the same speed into deep space, and has not stopped. This is an illustration of Newton's • 1st law. • 2nd law. • 3rd law.

1st law.

What is the net force when you combine a force of 7 N north with a force of 5 N south? • 2 N north. • 2 N south. • 12 N north. • 12 N south.

2 N north.

Your mother wants you to re-arrange your room for Thanksgiving to make room for your cousins. You try to hand off the task to your little brother, and tell him to move a heavy dresser out of the way. He can barely budge it, and it moves very slowly. You step into the task and find you can move it easily and swiftly. This is an example of Newton's • 1st law. • 2nd law. • 3rd law.

2nd law.

_______ is stored in a stretched rubber band. • Kinetic energy. • Potential energy. • Light energy. • Chemical energy.

Potential energy.

At what point does a roller coaster have the greatest kinetic energy? • The top of the biggest hill. • The bottom of the biggest hill. • The top of the smallest hill. • The bottom of the smallest hill.

The bottom of the biggest hill.

An orbit is formed when the space shuttle • moves forward because of inertia. • is pulled down by gravity. • The combination of both a and b.

The combination of both a and b.

If many forces are acting on an object in different directions, but the object does not move, we can say that the forces on that object are ________.

balanced

Which of the following vehicles has the LEAST kinetic energy? • Large truck traveling 50 m/s • minivan traveling 45 m/s • small car traveling 30 m/s • bicycle traveling 10 m/s

bicycle traveling 10 m/s

Plants, wood, and waste are all examples of • non-renewable resources. • inorganic matter. • biomass. • fossil fuels.

biomass.

Machines can: • increase energy. • transfer energy. • convert energy. • both transfer and convert energy.

both transfer and convert energy.

The United States' primary source of electrical energy is generated by • falling water. • the wind. • burning fossil fuels. • burning biomass.

burning fossil fuels.

A feather and a rock dropped at the same time from the same height would land at the same time when dropped • by Galileo in Italy. • by Newton in England. • by an astronaut on the moon. • by an astronaut on the space shuttle.

by an astronaut on the moon.

10. The unbalanced force that causes objects to move in a circular path is called ____________, and is caused by ____________.

centripetal force gravity

Gravitational force between 2 objects __________ as distance increases. (increases or decreases)

decreases

When you turn on a light bulb, you convert • potential energy into electrical energy and light energy. • electrical energy into kinetic energy and light energy. • electrical energy into light energy and thermal energy. • chemical energy into light energy and thermal energy

electrical energy into light energy and thermal energy.

If you're riding a horse and your horse suddenly stops just before a hurdle, you will most likely continue moving forward. This is explained in Newton's _________________ law of motion.

first

Inertia is used when explaining Newton's • first law of motion. • second law of motion. • third law of motion.

first law of motion.

Our most important nonrenewable resource is/are • solar energy. • wind energy. • fossil fuels. • geothermal energy.

fossil fuels.

When an object is falling and the only force acting on it is gravity (no air resistance), we say that the object is in:

free fall

The amount of gravity between 1 kg of lead and Earth is ___ the amount of gravity between 1 kg of cotton and Earth. • greater than • less than • the same as • None of the above.

the same as

Fossil fuels originally received their energy from • wind. • the sun. • water. • Earth's internal heat.

the sun.