PHY111 Final

If you raise a book to a greater height you are increasing its kinetic energy?

False

If you were to move into outer space far from any stars or planets, neither your weight nor your mass would change.

False

In an inelastic collision involving an isolated system, the final total momentum is more than the initial momentum?

False

Increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph require the same amount of work?

False

KE and momentum are always conserved?

False

KE can be a negative value?

False

The D=Vt equation is only valid if acceleration is constant

False

The following are units for impulse are kg*s/m?

False

The slope of a velocity versus time graph gives the position.

False

Two cars are traveling at the same constant speed v. Car A is moving along a straight section of the road, while car B is rounding a circular turn. Both cars are accelerating?

False

When adding vectors you add them tail to tail.

False

While standing still on a sloped surface, your weight is calculated by normal force

False

It is more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity.

True

It is theoretically possible to rotate a large cylindrical space station at just the proper speed so that the people inside will experience a force that feels just like gravity?

True

Power is the rate of doing work?

True

The Vf2 = Vi2 + 2a(∆R) equation is only valid if acceleration is a constant.

True

The work done by the normal force when sliding a book across a level table is zero?

True

To either stretch or compress a spring one must do positive work?

True

If the net force on an object is zero, it will slow down and eventually stop.

False

Is something always has a constant speed, then it can still accelerate

True

Every point on a rotating disk has the same linear velocity?

False

Consider the position versus time graph shown below. Which curve on the graph best represents a constantly accelerating motion?

A slopped line curved upward

What is the change in potential energy of an energetic 65 kg hiker who makes it from the floor of Death Valley, 85 m below sea level to the top of Mt.Whitney at 4420 m above sea level? A) 2.87x106 J B) 3.0 x106 J C) 4.4 x104 J D) 2.81 x106

A) 2.87x106 J

In 1971, Astronaut Alan B. Shepard Jr. hit 3 golf balls on the moon. The first two were 'duds', as it was hard to get a good swing (his suit weighed about 350 pounds on Earth, and is not very flexible), but the third went flying! If the gravity on Earth is 6 times that of the Moon, how many times further will a golf ball travel on the moon than one hit the same on Earth? Ignore wind resistance. A) 6 times C) 36 times E) same distance B) 1/6 as far D) 1/36 as far

A) 6 times

Why do most cars have anti-lock brakes, or why should you "pump" brakes in an older car if you wish to stop as quickly as possible? A) A "locked" tire invokes kinetic friction B) A "locked" tire invokes static friction

A) A "locked" tire invokes kinetic friction

A car is rounding a circular curve of radius r on a banked turn. As the figure shows, there are two forces acting on the car, its weight, mg, and the normal force, FN, exerted by the road. Which force, or force component, provides the centripetal force that keeps the car moving on the circular path? A) The horizontal component, FN sin, of the normal force. B) The vertical component, FN cos, of the normal force. C) The normal force, FN. D) The weight, mg, of the car.

A) The horizontal component, FN sin, of the normal force.

A box with a weight of 100N is at rest. It is then pulled by a 55N horizontal force as shown in the figure below. Will the box move? A) Yes 55N > fs max = 40N B) No C) Not enough information to say

A) Yes 55N > fs max = 40N

A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system A) is the same as before. B) is half as much as before. C) is one fourth as much as before. D) is one quarter as much as before.

A) is the same as before.

The centers of a 13 kg lead ball and a 70 g lead ball are separated by 0.14 m. What is the gravitational force between them? A) 3.1 x 10-6 N B) 3.1 x 10-9 N C) 4.3 x 10-11 N D) 4.3 x 10-9 N

B) 3.1 x 10-9 N

A hypothetical planet has a mass of one-half that of the earth and a radius of one-third that of the earth. What is the acceleration due to gravity on the planet in terms of g, the acceleration due to gravity at the surface of the earth? A) g B) 9/2 g C) 4g D) g/8 E) 2g

B) 9/2 g

All three 50kg blocks are at rest. The tension in rope 2 is: A) Greater than the tension in rope 1. B) Equal to the tension in rope 1. C) Less than the tension in rope 1.

B) Equal to the tension in rope 1.

Which requires more work, increasing a car's speed from 40 mph to 50 mph or from 50 mph to 60 mph? A) From 40 mph to 50 mph. B) From 50 mph to 60 mph. C) It is the same in both cases. D) The answer cannot be determined.

B) From 50 mph to 60 mph.

A uniform solid disk has mass M and radius R, and its moment of inertia about a central axis can be calculated as . If these are increased to 2M and 4R, what happens to the sphere's moment of inertia about a central axis? A) It increases by a factor of 54. B) It increases by a factor of 32. C) It increases by a factor of 16. D) It increases by a factor of 4.

B) It increases by a factor of 32.

Two identical satellites have different circular orbits shown. Which has a higher speed? A) The one in the larger orbit. B) The one in the smaller orbit. C) They have the same speed. D) The answer cannot be determined.

B) The one in the smaller orbit.

An elevator is suspended from a cable. It is moving upward at a steady speed. Which is the correct free-body diagram for this situation as shown in the diagram below.

Both arrows up and down should be equal

What is the minimum work done by the heart to pump 160 g of blood from a person's foot to his heart 1.5 m away? A) 0.24 J B) 240 J C) 2.4 J D) 24 J

C) 2.4 J

The velocity of a frog is 8m/s at 20° above the horizontal. What are the horizontal Vx and vertical Vy components of the frog's velocity. A) 7.3m/s, 2.7m/s B) 7.3m/s, 3.4m/s C) 7.5m/s, 2.7m/s D) 7.5m/s, 3.4m/s

C) 7.5m/s, 2.7m/s

Which one of the following statements concerning Newton's first law of motion is false? A) If no force acts on an object, the object's velocity cannot change. B) If no net force acts on an object, the object cannot accelerate. C) All objects in motion have net forces acting on them. D) All of the answers above are false.

C) All objects in motion have net forces acting on them.

An object is moving to the right in a straight line. The net force acting on the object is also directed to the right, but the magnitude of the force is decreasing with time. The object will A) continue to move to the right with a constant speed. B) stop and then begin moving to the left. C) continue to move to the right, with its speed increasing with time. D) continue to move to the right, with its speed decreasing with time.

C) continue to move to the right, with its speed increasing with time.

A frog is resting on a sloped tree branch, as shown in the picture below. The frog has a weight of 5 N. What can you say about the magnitude of the normal force acting on the frog? A) n > 5 N. B) n = 5 N. C) n < 5 N. D) It cannot be determined.

C) n < 5 N

A stalled car is being pushed up a hill by three people, and it is moving at a constant speed. The net force on the car is A) in the opposite direction of the car's motion. B) in the same direction of the car's motion. C) zero. D) None of the above.

C) zero.

You want to store 1,000 J of energy in an ideal spring when it is compressed by only 2.5 cm. What should be the force constant (spring constant) of this spring? A) 4.0 x 106 N/m B) 8 x 104 N/m C) 1.6 x 106 N/m D) 3.2 x 106 N/m

D) 3.2 x 106 N/m

A ring, as seen from above is pulled on by three forces. The ring is not moving. How big is the force F? A) 20N B) 30N cosƟ C) 20N sinƟ D) 30N sinƟ

D) 30N sinƟ

You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top. A) It is impossible to tell, since the times you both took are unknown. B) It is impossible to tell, since the distances you both traveled are unknown. C) Your friend's gravitational potential energy is greater than yours, because he got to the top faster. D) Both of you have the same amount of gravitational potential energy at the top. E) Your gravitational potential energy is greater than that of your friend, because you traveled a greater distance in getting to the top.

D) Both of you have the same amount of gravitational potential energy at the top.

If a stone is dropped with an initial gravitational potential energy of 100 J but reaches the ground with a kinetic energy of only 75 J, this is a violation of the principle of conservation of energy?

False

If an elevator is speeding up while moving down its Fnet is in the upwards direction.

False

If something always has a constant velocity, then it can still accelerate

False

"Giddy-up horsey"! A horse pulls on a cart and the cart pulls back on the horse; do these two opposing forces cancel? If you are not careful with the logic, and the physics, you might come to the conclusion that no matter how hard the horse pulls, it can never move the cart. But you know a horse can pull a cart in "real life", so where is the flaw in this reasoning? The action and reaction forces do not cancel each other out because: A) the action and reaction forces do not cancel each other out because they are not equal in magnitude in this situation. B) they are equal in magnitude, but not precisely opposite in direction. C) they are equal in mag., opposite in direction, but do not act at the same time. D) they are not acting on the same body.

D) they are not acting on the same body.

The fan blade is slowing down. What are the signs of ω and α? A) ω is positive and α is positive. B) ω is positive and α is negative. C) ω is negative and α is negative. D) ω is negative and α is positive

D) ω is negative and α is positive

How fast would you have to throw something straight up to make it go 1776 feet (or 541 meters) vertically into the air. Neglect air resistance. A) Between 50 and 60 m/s. D) Between 80 and 90 m/s B) Between 60 and 70 m/s. E) More than 100 m/s. C) Between 70 and 80 m/s.

E) More than 100 m/s.

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car. A) Joel does 75% more work than Jerry. B) Joel does 50% more work than Jerry. C) Jerry does 50% more work than Joel. D) Joel does 25% more work than Jerry. E) Neither of them does any work.

E) Neither of them does any work.

Jill does twice as much work as Jack does and in half the time. Jill's power output is A) the same as Jack's power output. B) one-fourth as much as Jack's power output. C) one-half as much as Jack's power output. D) twice Jack's power output. E) four times Jack's power output.

E) four times Jack's power output.

A 500-kg object moving at 40 m/s and a 1000-kg object moving at 20 m/s, both have the same kinetic energy?

False

A Newton (N) is kg m^2/s^2.

False

A ball at the end of a string being swung in a vertical circle at a constant speed is not accelerating?

False

A ball is thrown vertically upward and then comes back down. During the ball's flight up and down, its velocity and acceleration vectors are constant.

False

Air bags protect people by decreasing the change in momentum suffered during crashes?

False

An object thrown horizontally from a building hits sooner than if dropped

False

Because of the t-squared, x = xo + vot + (1/2)at2 is valid if "a" changes in time.

False

A nut needs to be tightened with a wrench. Which force shown below will apply the greatest torque to the nut?

Force all the way out and straight down on handle

If an object remains at rest, then the sum of both the external torques and the external forces on the object must be zero?

True

A Torque > 0 produces a change in angular momentum (τnet = ∆L)?

True

A kangaroo has tendons in its legs that actually stretch and store some of the (elastic potential) energy in each bounce so that it can be used for another bounce.

True

A leaning car is stable if its center of mass is exactly over its pivot point?

True