Physics Exam 1

Check all statements that describe an object at equilibrium. - A car rounds a curve at a constant 30 mph. - A ball is dropped from rest. - A box sits on the floor. - A crate is pulled across the floor with a 5 N force and is resisted by a 5 N frictional force. - A hockey puck moves uniformly 1 m/s in a straight line. - A bicycle slows to a stop.

- A box sits on the floor. - A crate is pulled across the floor with a 5 N force and is resisted by a 5 N frictional force. - A hockey puck moves uniformly 1 m/s in a straight line.

What is the acceleration of the ball at the moment a ball has zero velocity? -10 m/s per second (down) 10 m/s per second (up) 0 m/s per second There's no way to know this

-10 m/s per second down

A theory in science ____. Is something that would have been called a law in Newton's time. Is a very well tested idea that has failed no crucial test of its validity Is forever true Might fail a crucial test at some point in the future. Is an educated guess

-is something that would have been called a law in Newton's time. -might fail a crucial test at some point in the future. -is a very well tested idea that has failed no crucial test of its validity

What is the acceleration of a car that maintains a constant velocity of 100 km/h for 10 s? 1 km/h·s 10 km/h·s 0.1 km/h·s 0 km/h·s

0 km/h·s

Given the measurements 10 m, 10 m/s, and 10 m/s2, which is a measure of speed, which is a measure of distance, and which is a measure of acceleration? 10 m is acceleration, 10 m/s is speed, and 10 m/s2 is distance. 10 m is distance, 10 m/s is speed, and 10 m/s2 is acceleration. 10 m is distance, 10 m/s is acceleration, and 10 m/s2 is speed. 10 m is speed, 10 m/s is distance, and 10 m/s2 is acceleration.

10 m is distance, 10 m/s is speed, and 10 m/s2 is acceleration.

What's the velocity of a ball 1 s before it reaches its highest point? -(-)10 m/s per second (down) -(-)10 m/s (down) -10 m/s (up) -10 m/s per second (up)

10 m/s (up)

When a ball thrown straight upwards reaches the very top of its path, its acceleration is 5 m/s2. 10 m/s2. zero. none of the above

10 m/s2.

While you are in a bus that moves at 100 km/h you walk from the back to the front at 10 km/h. What is your speed relative to the road outside? 110 km/h. 90 km/h 100 km/h 10 km/h

110 km/h

What is the net force when a 5-N force and a 10-N force simultaneously act in the SAME direction on an object? 15 N 0 N 10 N 5 N

15 N

Consider a book that weighs 15 N at rest on a flat table. How many newtons of support force does the table exert on the book? 15 newtons down 0 newtons 15 newtons up 30 newtons up

15 newtons up

A ball freely falling at 20 m/s will in the next second have a speed of ______. 10 m/s. 30 m/s more than 30 m/s 20 m/s

30 m/s

In its first second of free fall, a dropped softball will fall a vertical distance of ______. (Recall that distance fallen is 1/2 (g) times the square of time, when you neglect air resistance.) 5 m 10 m 15 m 20 m

5 m

The force of friction on a sliding object is 6 N. The applied force needed to maintain a constant velocity is - 6 N. - more than 6 N. - less than 6 N.

6 N

Why do we say that force is a vector quantity? A force is a scalar quantity. A force is measured in pounds, and pounds are a vector quantity. A force has a magnitude and a direction. A force has a magnitude, but not a direction.

A force has a magnitude and a direction.

Distinguish between a hypothesis and a theory. A hypothesis and a theory have both been tested and verified by experiment. A hypothesis is an educated guess, whereas a theory encompasses well tested and verified hypotheses. A hypothesis and a theory are both educated guesses. A theory is an educated guess, whereas a hypothesis has been tested and verified by experiment.

A hypothesis is an educated guess, whereas a theory encompasses well tested and verified hypotheses.

What is the test for whether a hypothesis is scientific or not? A hypothesis is scientific if it can be written as an equation. A hypothesis is scientific if it is possible to prove it wrong. A hypothesis is scientific if the appropriate scientific body says it is. A hypothesis is scientific if it is possible to prove it right.

A hypothesis is scientific if it is possible to prove it wrong.

What does it mean to say something is in mechanical equilibrium? An object in mechanical equilibrium experiences a net force twice its weight. An object in mechanical equilibrium is always in motion. An object in mechanical equilibrium experiences a zero net force. An object in mechanical equilibrium must experience no forces.

An object in mechanical equilibrium experiences a zero net force.

If an object moves with constant acceleration, it's velocity must: Be constant also Change by the same amount each second Change by varying amounts depending on its speed Always decrease

Change by the same amount each second

The complexity of Ptolemy's model was an indicator that his theory was inherently flawed. Why, then, was the geocentric model the leading theory for such a long time, even though the heliocentric model more simply explained the observed motions and brightness of the planets? Check all that apply. The heliocentric model did not make noticeably better predictions than the geocentric model. The geocentric model conformed to both the philosophical and religious doctrines of the time. From Earth, all heavenly bodies appeared to circle around Earth, while Earth remained still. The complexity of the geocentric model was appealing to most ancient astronomers. Ancient astronomers did not observe stellar parallax, which would have provided evidence in favor of the heliocentric model.

Every answer except the complexity of the geocentric model was appealing to most ancient astronomers.

What are the units for force? Force must be measured in newtons; it can never be measured in pounds. Force must be measured in pounds and then converted to newtons. Force can be expressed in newtons or pounds. Force must first be measured in newtons, then converted to pounds.

Force can be expressed in newtons or pounds.

What did Galileo discover in his legendary experiment on the Leaning Tower of Pisa? Galileo found that stones fall faster proportional to their weight. Galileo found that a heavier stone falls at essentially the same rate as a lighter one. Galileo found that a heavier stone falls significantly faster than a lighter one. Galileo found that air resistance significantly slowed falling stones.

Galileo found that a heavier stone falls at essentially the same rate as a lighter one.

Equations in Conceptual Physics are used mainly _______. Recipes for problem solving. A means of highlighting the mathematical structure of physics. Guides to thinking. Experimental tools.

Guides to thinking.

Sort each statement according to whether it is an advantage of the heliocentric model, the geocentric model, or both.

Heliocentric- Explained planetary motions and brightness changes most simply. Geocentric- Rooted in widely accepted religious beliefs regarding Earth's place in the universe. Both- Planetary orbits and motions based on Greek ideologies of perfect form and motion. Predicted planetary positions accurately over relatively short time periods. (they both took a long time so one is not quicker than the other. therefore, they're both under this category)

Testable vs not testable. Distinguish which are NOT testable by science. People born under the sign of Sagittarius are twice as likely to be teachers as anyone else. Mars once had liquid water on its surface. Bacteria acquire resistance to antibiotics through changes in their DNA. Earth orbits the Sun every 365.25 days. Hurricane Katrina was an act of God. There will be a solar eclipse next Tuesday at 11 am. Vince Young is the greatest quarterback of all time.

Hurricane Katrina was an act of God. Vince Young is the greatest quarterback of all time.

What did Galileo discover about moving bodies and force in his experiments with inclined planes? - Bodies rolling down an inclined plane slowed down. - Bodies rolling down a steep inclined plane starting at a given height rolled up a gently inclined plane to a higher height. - In the absence of a frictional force, a body will keep moving at a constant speed in a straight line forever. - Bodies rolling up an inclined plane sped up.

In the absence of a frictional force, a body will keep moving at a constant speed in a straight line forever.

You make a right turn while driving and your body presses into the driver door on your left. What have we discussed that explains this? Weight Friction Gravity at Earth's surface Inertia

Inertia

What type of path does a moving object follow in the absence of a force? - It follows a parabolic trajectory in the absence of a force. - It moves in a straight line and eventually slows to a stop. - It follows a circular path in the absence of a force. - It continues to move in a straight line at a constant speed.

It continues to move in a straight line at a constant speed.

What is the gain in speed per second for a freely falling object? It gains approximately 10 m/s. It gains 0 m/s. It gains 10 m/s2. It loses 10 m/s.

It gains approximately 10 m/s.

When an object is thrown upward, how much speed does it lose each second (ignoring air resistance)? It loses 10 m/s of speed each second until it reaches the high point, then it gains 10 m/s each second. It loses 10 m/s each second. It loses 1 m/s of speed each second.

It loses 10 m/s of speed each second until it reaches the high point, then it gains 10 m/s each second.

If a car is moving at 90 km/h and it rounds a corner, also at 90 km/h, does it maintain a constant speed? A constant velocity? It does not maintain a constant speed or a constant velocity. It maintains a constant speed and a constant velocity. It maintains a constant speed, but does not maintain a constant velocity. It maintains a constant velocity, but not a constant speed.

It maintains a constant speed, but does not maintain a constant velocity.

What two classes of motion did Aristotle advocate? Natural motion and violent motion Vertical motion and horizontal motion Propelled motion and passive motion Earthly motion and heavenly motion

Natural and violent motion

The amount of force needed to sustain motion of a rock in outer space is - a force equal to its weight. - a force slightly less than its weight if friction is absent. - No force at all is needed.

No force at all is needed.

Two competing models attempt to explain the motions and changing brightness of the planets: Ptolemy's geocentric model and Copernicus' heliocentric model. View the animations in Hints 1 and 2 to explore these two models and then decide which one used epicycles and deferents to explain planetary motion in which a planet temporarily appeared to move backwards and then resumed moving in the original direction of motion. Both models Ptolemy's geocentric model Neither model Copernicus' heliocentric model

Ptolemy's geocentric model

The Greek mathematician Eratosthenes made measurements to show the size of ______. Earth Sun Moon All of these

The Earth

When the Sun was directly overhead in Syene, why wasn't it directly overhead in Alexandria? Gravity bends light. Seen is in a diff. time zone than Alexandria. The Sun is a sphere. The Earth is a sphere.

The Earth is a sphere.

What can you say about the result of adding a 3 unit vector pointing to the right and a 4 unit vector pointing up? The answer is a 1 unit vector. You can't add these vectors. The answer is a 7 unit vector. The answer can not be found by simple addition of 3 and 4 because they are at right angles to each other. You must use a method that takes perpendicular direction into account.

The answer can not be found by simple addition of 3 and 4 because they are at right angles to each other. You must use a method that takes perpendicular direction into account.

If you push on a crate with a horizontal force of 100 N and it slides at constant velocity, what is the magnitude and direction of the frictional force acting on the crate? - The frictional force on the crate is 100 N in the same direction as the direction of motion. - The frictional force on the crate is zero newtons. - The frictional force on the crate is 100 N opposite the direction of motion. - The frictional force has nothing to do with you pushing on the crate.

The frictional force on the crate is 100 N opposite the direction of motion.??? whyyyy

What is the net force on a cart that is pulled to the right with 100 pounds of force and to the left with 30 pounds of force? The net force is 130 pounds. The net force is 70 pounds to the right. The net force is 70 pounds to the left. The net force is zero.

The net force is 70 pounds to the right.

What is the net force on an object that is pulled with forces of 80 newtons to the right and 80 newtons to the left? The net force is 160 newtons to the right. The net force is 113 newtons downward. The net force is 113 newtons upward. The net force is zero newtons.

The net force is zero newtons.

What is the net force on an object in either static or dynamic equilibrium? - The net force is vertical for static equilibrium and horizontal for dynamic equilibrium. - The net force is equal and opposite to the weight of the object. - The net force is zero. - The net force is zero for static equilibrium and greater than zero for dynamic equilibrium.

The net force is zero.

A ball rolling down an inclined plane each second picks up ______. - the same amount of speed each second - decreasing amounts of speed each second. - increasing amounts of speed each second. - acceleration, not speed.

The same amount of speed each second

What is the speed acquired by a freely falling object 5 s after being dropped from a rest position? What is the speed 6 s after? The speed is 2 m/s after 5s and 1.7 m/s after 6 s. The speed is 60 m/s after 5 s and 50 m/s after 6s. The speed is 50 m/s after 5 s and 60 m/s after 6 s. The speed is 5 m/s after 5 s and 6 m/s after 6 s.

The speed is 50 m/s after 5 s and 60 m/s after 6 s.

What are the circular spots of light seen on the ground beneath a tree on a sunny day? These are blurry images of the point of light that is the Sun. These are pinhole images of the Sun. These are images of holes formed by gaps between leaves. These are images of holes in leaves.

These are pinhole images of the Sun.

Consider the video demonstration that you just watched. Which of the following is consistent with what you saw in the video? - If we want the ball to strike the yellow can we just need to use a ball that is heavier than the original ball. - When the force making the ball move in a circle is removed, the ball continues moving in a circle at uniform speed. - If we want the ball to strike the green can we just need to roll the ball faster. - When the force making the ball move in a circle is removed, the ball's inertia keeps it going at a steady speed in a straight line.

When the force making the ball move in a circle is removed, the ball's inertia keeps it going at a steady speed in a straight line.

A scientific hypothesis deemed valid must have a test for proving it ______. more than one time none of these correct wrong

Wrong

Rank them, from greatest to least, by the force needed to keep them moving at their given speeds. 2 m/s, 4 m/s, 6 m/s

all are equal to each other

A man stands at rest on two bathroom scales so that his weight is evenly distributed over both scales. The scale readings... add up to equal his weight. each read half his weight. will change if he slightly shifts to the right. all of the answers are true.

all are true

The acceleration due to Earth's gravity at Earth's surface (g) is approximately ..... may be up, down, or 0 for an object thrown upward always 10 m/s/s downward always 10 m/s downward Is the same as velocity in freefall

always 10 m/s/s downward

If while riding in a smooth-riding train, you toss a coin upward, the coin will normally land ______. -off to the side of your location - when you toss the coin - behind you - in your hand - in front of you

in your hand

The distance a freely falling bowling ball falls each second is about 5 m. increases. is about 10 m. none of the above

increases

Check all that are true for an object that is experiencing a net force.... it may have a curved path. it is not at equilibrium its acceleration must be changing its velocity must be changing

it may have a curved path. it is not at equilibrium its velocity must be changing

What is equal to zero at the top of the path of a ball thrown upward? - only velocity - both velocity and acceleration - neither velocity nor acceleration - only acceleration

only velocity

Whenever a net force acts on an object, there is a change in the object's _______. velocity. speed direction shape.

velocity