Physic hw chp 2

If you push on a crate with a horizontal force of 100N and it slides at a constant velocity, what is the magnitude and direction if the frictional force acting on the crate? A. Has nothing to do with you pushing the crate B. Is 100N opposite the direction of motion C. Is 100N in the same direction as the direction of motion D. Is zero newtons

B. Is 100N opposite the direction of motion

What are he units of force? A. Force must be measured in pounds and then converted to newtons. B. force can be expressed in newtons or pounds C. Force must first be measured in newtons, then converted to pounds D. Force must be measured in newtons, it can never be measured in pounds

B. force can be expressed in newtons or pounds

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

B. it continues to move in a straight line at a constant speed.

According to the parallelogram rule, what quantity is represented by the diagonal of a constructed parallelogram? A. The diagonal is 1.41 times the magnitude of the longest vector B. the diagonal is the resultant, or sum, of two vectors C. The diagonal is the difference of two vectors D. The diagonal is always 1.41 times the magnitude of the sum of the vectors

B. the diagonal is the resultant, or sum, of two vector

A ball rolling along a floor doesn't continue rolling indefinitely. Is it because it is seeking a place to rest or because some force is acting on it? If so, identify the force.

It is because some force is acting upon It . Friction

What Aristotelian idea did Galileo demolish with his experiments with inclined planes?

The idea that an object required a push or pull to keep moving

What is the net force on an object I either static or dynamic equilibrium? A. Net force is zero B. Net force is zero for static and greater than zero for dynamic C. Equal and opposite to the weight of the object D. Vertical for static and horizontal for dynamic

A. Net force is zero

A bowling ball at rest is in equilibrium. Is the ball in equilibrium when it moves at a constant speed in a straight line? A. Yes, because £F=0 B. No, because £F=-mg C. No, because it is moving D. No, because the wood of the bowling alley exerts an upward force on the ball

A. Yes, because £F=0

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? A. 160 newtons to the right B. 113 newtons upward C. 113 newtons downward D. Zero newtons

D. Zero newtons

What state of motion did Aristotle attribute to earth? A. Natural B. violent C. In free fall D. In circular motion

A. Natural

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

C. A force has a magnitude and a direction

What does it mean to say something is in mechanical equilibrium? A. It experiences a net force twice it's weight B. is always in motion C. Experiences a zero net force D. Must experience no forces

C. Experiences a zero net force

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

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

What class of motion did Aristotle attribute to the moon? A. Violent B. At rest C. Natural D. Continuous

C. Natural

What is the net force on a bag pulled down by gravity with a force of 18N and pulled upward by a rope with a force of 18N? A. 36N B. 25N C. 18N D. Zero N

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What Aristotelian idea did Galileo discredit in his fabled leaning tower demonstration.?

Aristotle's falling-body hypothesis

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

B. 15 N up

What did Galileo discover in his legendary experiment on the leaning tower of Pisa? A. Galileo found that air resistance significantly slowed falling stones B. Galileo found that a heavier stone does not fall significantly faster than a lighter one C. He found that a heavier stone falls significantly faster than a lighter one D. He found the stones fall faster proportional to their weight

B. Galileo found that a heavier stone does not fall significantly faster than a lighter one

How does Newton's first law of motion relate to Galileo's concept of inertia? A. Newton expressed Galileo concept of inertia with the inertia equation B. Newton refined Galileo concept of inertia and made it his first law of motion C. Newton first law of motion refuted Galileo concept of inertia D.newton replaced Galileo concept of inertia with his three laws of motion

B. Newton refined Galileo concept of inertia and made it his first law of motion

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? A. The net force is 70 pounds to the left B. the net force is 70 pounds to the right C. The net force is 130 pounds D.the net force is zero

B. the net force is 70 pounds to the right

When you stand at rest on a bathroom scale, how does your weight compare with the support force from the scale? A. Your weight is equal in magnitude and in the same direction as the support B. your weight is equal in magnitude and opposite in direction to the support force C. The support force is half your weight D. The support force is twice your weight

B. your weight is equal in magnitude and opposite in direction to the support force

What relationship between the sun and earth did Copernicus formulate? A. The earth was at rest with respect to the sun B. the sun and the earth revolve in circles around each other C. The earth revolved in a circle about the sun D. The sun revolved in a circle about the earth

C. The earth revolved in a circle about the sun

State the equilibrium rule of forces in symbolic notation: A. £F =2mg B. £F= -mg C. £F=0 D. £F= net force

C. £F=0

What concept was not understood in the 16th century when people couldn't conceive of a moving earth? A. Relativity B. Net force C. Parallelogram law of force addition D. Inertia

D. Inertia

A bird sitting in a tree is traveling at 30km/s relative to the faraway sun. When the bird drops to the ground below, does it still move at 30km/s or does this speed become zero A. It has a speed of 30km/s relative to the ground and sun B. It comes to rest relative to the sun and the ground C.it has a speed of 30km/s relative to the sun and -30km/s relative to the earth D. It continues to move at 30km/s relative to the sun, but has a speed of 0km/s relative to the ground

D. It continues to move at 30km/s relative to the sun, but has a speed of 0km/s relative to the ground

What is inertia? A. Inertia explains why things stay at rest but not why they stay on motion B. it described why it is easier to get a massive ball moving than it is to get a less massive one moving C. It explains why things stay in motion but not why they stay at rest. D. It is the tendency of a body to maintain its state of motion in the absence of applied forces

D. It is the tendency of a body to maintain its state of motion in the absence of applied forces

Consider Nellie hanging at rest. If the ropes were vertical, with no angle involved, what would be the tension in each rope? A. Tension in each rope would be twice the gravity force B. tension would be zero in both ropes C. Tension in each rope would be equal to the gravity force D. The tension in each rope would be half of the gravity force

D. The tension in each rope would be half of the gravity force

What is the resultant of a pair of one pound forces at right angles of each other? A. A force of 2.0lbs in a direction bisecting the angle between the two vectors B. a force of 1.0lbs in a direction bisecting the angle between the two vectors C. Zero force D.a force of 1.41lbs in a direction bisecting the 90 degree angle between the two vectors

D.a force of 1.41lbs in a direction bisecting the 90 degree angle between the two vectors

Your friend says that inertia is a force that keeps things in their place, either at rest or in motion. Do you agree? Why or why not?

No, because inertia is a property not a force