Exam 1 Review

The mass of a pet turtle that weighs 10 N is about A. 1 kg. B. 10 kg. C. 100 kg. D. 1000 kg.

A. 1 kg.

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 circular path in the absence of a force. D. It follows a parabolic trajectory 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 vectors.

What are steps of the scientific method. A. Using Occam's razor to eliminate excess facts. B. Hypothesis, predictions, and experimental findings. C. Reasoning and derivation from axioms. D. Assembling and organizing facts and checking them against dogma.

Correct B. Hypothesis, predictions, and experimental findings.

A car has a mass of 1000 kg and accelerates at 2 m/s2. What net force is exerted on the car? A. 500 N B. 1000 N C. 1500 N D. 2000 N E. none of these

D. 2000 N

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 A. 0 m/s2. B. 5 m/s2. C. 8 m/s2. D. 24 m/s2.

A. 0 m/s2.

How does acceleration depend on the net force? A. Acceleration is proportional to the net force. B. Acceleration is equal to the net force. C. Acceleration is inversely proportional to the net force. D. Acceleration is independent of the net force.

A. Acceleration is proportional to the net force.

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

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

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? A. It maintains a constant speed, but does not maintain a constant velocity. B. It maintains a constant speed and a constant velocity. C. It does not maintain a constant speed or a constant velocity. D. It maintains a constant velocity, but not a constant speed.

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

When you are struck by a moving object, is it favorable that the object makes contact with you over a short time or over a long time? A. Long contact time decreases the magnitude of the average force and is favorable. B. Short contact time increases the magnitude of the average force and is favorable. C. Short contact time decreases the magnitude of the average force and is favorable. D. Long contact time increases the magnitude of the average force and is favorable.

A. Long contact time decreases the magnitude of the average force and is favorable.

What is the acceleration of a falling object that has reached its terminal velocity? A. The acceleration is 0. B. The acceleration is g. C. The acceleration is -g. D. The acceleration is g2.

A. The acceleration is 0

If the mass of a sliding block is tripled while a constant net force is applied, by how much does the acceleration change? A. The acceleration is reduced to 1/3 of its original value. B. The acceleration triples. C. The acceleration remains the same. D. The acceleration is zero.

A. The acceleration is reduced to 1/3 of its original value.

If you double the net force on an object, you'll double its A. acceleration. B. speed. C. velocity. D. all the above

A. acceleration.

The team to win in a tug-of-war is the team that _______. A. pushes harder on the floor while holding the rope B. has the greatest self confidence C. yanks the rope. D. pulls with the greater force

A. pushes harder on the floor while holding the rope

A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. During this interval its acceleration is A. zero. B. 1 m/s2. C. 10 m/s2. D. none of the above

B. 1 m/s2.

A 10-N block and a 1-N block lie on a horizontal friction-less table. To impart equal horizontal accelerations, we would have to push the heavier block with A. an equal force. B. 10 times as much force. C. 10 squared or 100 times as much force. D. 1/10 as much force. E. none of the above

B. 10 times as much force.

What is the weight of a 5-kilogram brick resting on a table? A. 0.5 N B. 50 N C. 5 N D. 50 kg

B. 50 N

41 If the forces that act on a cannonball and the recoiling cannon from which it is fired are equal in magnitude, why do the cannonball and cannon have very different accelerations? A. The cannon pushes on the cannon ball with a much greater force than the cannon ball pushes on the cannon. B. Remember F = ma, and note that the cannon has a much greater mass than the cannon ball, so the cannon accelerates less for the same force. C. The force from the cannon ball on the cannon produces little acceleration because it lasts for such a brief time. D. The cannon weighs so much that friction with the ground alone prevents it from accelerating.

B. Remember F = ma, and note that the cannon has a much greater mass than the cannon ball, so the cannon accelerates less for the same force.

The support force on a 30-kg dog sleeping on the floor is A. less than 300 N. B. about 300 N. C. more than 300 N. D. nonexistent while asleep.

B. about 300 N.

Galileo taught us that if you roll a ball along a level surface it will A. soon slow down due to its natural place. B. keep rolling if friction is absent. C. roll as long as its inertia nudges it along. D. soon roll in the opposite direction.

B. keep rolling if friction is absent.

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will A. move in the opposite direction at 20 m/s. B. move in the opposite direction at a lower speed. C. move in the opposite direction at a higher speed. D. none of the above

B. move in the opposite direction at a lower speed.

A crate sits at rest on a factory floor. Friction between the crate and floor occurs _______. A. only if the crate is pushed vertically as well as horizontally B. when the crate is pushed horizontally, whether sliding or not. C. only if the crate is sliding. D. even when no pushing occurs.

B. when the crate is pushed horizontally, whether sliding or not.

A 1-kg glider travels at 1m/s and collides with a 2-kg glider at rest on an air track. They collide and stick. The combined mass moves at A. 0 m/s. B. 1/2 m/s. C. 1/3 m/s. D. 1/6 m/s. E. 1.5 m/s.

C. 1/3 m/s.

The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is A. more than 10 N. B. less than 10 N. C. 10 N.

C. 10 N

What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10 s? A. 1km/h•s B. 100 km/h•s C. 10 km/h•s D. 10 m/s2

C. 10 km/h•s

40 When a baseball player bats a ball with a force of 1000 N, the reaction force that the ball exerts against the bat is A. less than 1000 N. B. more than 1000 N. C. 1000 N. D. need more information

C. 1000 N.

How far does a horse travel if it gallops at an average speed of 25 km/h for 30 min? A. 0.83 km B. 50 km C. 12.5 km D. 750 km

C. 12.5 km

The resultant of a 40-N force at right angles to a 30-N force is A. 30 N. B. 40 N. C. 50 N. D. greater than 50 N.

C. 50 N.

A 10-N falling object encounters 4 N of air resistance. The net force on the object is A. 0 N. B. 4 N. C. 6 N. D. 10 N.

C. 6 N.

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

C. An object in mechanical equilibrium experiences a zero net force.

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

C. The Earth revolved in a circle about the Sun.

For the same force, why does a long cannon impart more speed to a cannonball than a short cannon? A. The force is applied for a longer time in the short cannon. B. The force is applied for a shorter time in the long cannon. C. The force is applied for a longer time in the long cannon. D. The force per unit time is greater for a long cannon.

C. The force is applied for a longer time in the long cannon.

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? A. The frictional force on the crate is zero newtons. B. The frictional force has nothing to do with you pushing on the crate. C. The frictional force on the crate is 100 N opposite the direction of motion. D. The frictional force on the crate is 100 N in the same direction as the direction of motion.

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

Why doesn't a heavy object accelerate more than a light object when both are freely falling? gravity force. A. The inertia of the heavy object is just enough smaller than the inertia of the lighter object to counteract the larger B. The inertia of the heavy object equals the inertia of the lighter object, so their accelerations are the same. C. The ratio of the weight to mass is the same for all objects in the same locality. D. The larger air resistance force on the larger object makes it fall with the same acceleration.

C. The ratio of the weight to mass is the same for all objects in the same locality.

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? A. The speed is 2 m/s after 5s and 1.7 m/s after 6 s. B. The speed is 60 m/s after 5 s and 50 m/s after 6s. C. The speed is 50 m/s after 5 s and 60 m/s after 6 s. D. The speed is 5 m/s after 5 s and 6 m/s after 6 s.

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

When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is A. less than 1/10 as great. B. more than 1/10 as great. C. about 1/10 as great. D. about 10 times as great.

C. about 1/10 as great.

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 A. follow a circular path. B. slow down. C. follow a straight-line path. D. stop.

C. follow a straight-line path.

A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater A. speed. B. acceleration. C. momentum. D. all of the above E. none of the above

C. momentum.

Two factors that greatly affect air resistance on falling objects are frontal area and A. mass. B. weight. C. speed.

C. speed.

The winner in a tug-of-war exerts the greatest force on A. the opponent. B. his or her end of the rope. C. the ground.

C. the ground.

A force of 1 N accelerates 1-kg box at the rate of 1 m/s2. The acceleration of a 2-kg box by a net force of 2 N is A. half as much. B. twice as much. C. the same. D. none of the above

C. the same.

You cannot exert a force on a wall A. if the wall resists. B. unless you put your mind to it. C. unless the wall simultaneously exerts the same amount of force on you.

C. unless the wall simultaneously exerts the same amount of force on you.

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? A. 90 km/h B. 110 km/h. C. 100 km/h D. 10 km/h

Correct

Railroad car A rolls at a certain speed and makes a perfectly elastic collision with car B of the same mass. After the collision, car A is observed to be at rest. How does the speed of car B compare with the initial speed of car A? A. The speed of car B is half the initial speed of car A. B. The speed of car B is zero. C. The speed of car B is twice the initial speed of car A. D. The speed of car B is equal to the initial speed of A.

D. The speed of car B is equal to the initial speed of A.

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

D. Your weight is equal in magnitude and opposite in direction to the support force from the scale.

A vehicle undergoes acceleration when it A. gains speed. B. loses speed. C. changes its direction. D. all of the above

D. all of the above

For every action force, there must be a reaction force that A. acts in the same direction. B. is slightly smaller in magnitude than the action force. C. is slightly larger in magnitude than the action force. D. is equal in magnitude.

D. is equal in magnitude.

A slowly moving ship can have a greater momentum than a fast moving racing car when _______. A. it drifts toward a distant port. B. its speed is greater than the speed of the car. C. its mass is greater than the mass of the car D. its mass times velocity is greater than that of the car.

D. its mass times velocity is greater than that of the car.

What does the conservation of momentum say about collisions in general? A. if the collision is inelastic. B. only if deformation of either vehicle does not occur. C. if the collision is elastic D. whether the collision is elastic or inelastic.

D. whether the collision is elastic or inelastic.