University Physics Final

Which of the following free-body diagrams best represent the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward with a constant velocity? Ff is the force of the floor on the person and F is the force of gravity on the person.

B

A box slides down a frictionless plane inclined at an angle 0 above the horizontal. The gravitational force on the box is directed…

A) at an angle 0 below the inclined plane.

B) parallel to the plane in the same direction as the movement of the box.

C) vertically.

D) parallel to the plane in the opposite direction as the movement of the box.

E) perpendicular to the plane.

C)

You are seated in a bus and notice that a hand strap that is hanging from the ceiling hangs away from the vertical in the backward direction. From this observation, you can conclude that…

1. the velocity of the bus is forward.

2. the velocity of the bus is backwara.

3. You cannot conclude anything about the direction of the velocity of the bus.

3.

Two objects have masses m and 5m, respectively. They both are placed side by side on a frictionless inclined plane and allowed to slide down from rest.

1. The two objects reach the bottom of the incline at the same time.

2. It takes the lighter object 10 times longer to reach the bottom of the incline than the heavier object.

3. It takes the heavier object 5 times longer to reach the bottom of the incline than the lighter object.

4. It takes the lighter object 5 times longer to reach the bottom of the incline than the heavier object.

5. It takes the heavier object 10 times longer to reach the bottom of the incline than the lighter object.

1.

You swing a bat and hit a heavy box with a force of 1500 N. The force the box exerts on the bat is 5)

1. exactly 1500 N only if the box does not move.

2. exactly 1500 N whether or not the box moves.

3. greater than 1500 N if the box moves.

4. greater than 1500 N if the bat bounces back.

5. less than 1500 N if the box moves.

Two

Vector A has a magnitude 5.00 and points in a direction 40.0° clockwise from the negative y axis. What are the r and y components of vector A

1. Ax = -3.21 and Ay = -3.83

2. Ax = 3.83 and Ay = -3.21

3. Ax = 3.83 and Ay = 3.21

4. Ax = 4.29 and Ay = 2.16

5. Ax = -3.21 and Ay = 3.83

1.

Consider what happens when you jump up in the air. Which of the following is the most accurate statement?

1. When you jump up the earth exerts a force F1 on you and you exert a force Ez on the earth. You go up because F1 > F2•

2. You are able to spring up because the earth exerts a force upward on you that is greater than the downward force you exert on the earth.

3. It is the upward force exerted by the ground that pushes you up, but this force cannot exceed your weight.

4. Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it’s the internal forces of your muscles acting on your body itself that propels your body into the air.

5. When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air.

5.

A brick is resting on a rough incline as shown in the figure. The friction force acting on the brick, along the incline, is…

two

Which of the following is an accurate statement?

1. Rotating a vector about an axis passing through the tip of the vector does not change the vector.

2. The magnitude of a vector can be zero even though one of its components is not zero.

3. It is possible to add a scalar quantity to a vector.

4. Even though two vectors have unequal magnitudes, it is possible that their vector sum is

5. The magnitude of a vector is independent of the coordinate system used.

5.

The rabbit trying to escape the fox runs north for 8 meters, darts northwest for 1 meter, then drops 1 meter down into a hole in its burrow. What is the magnitude of the net displacement of the rabbit?

1. 10m

2. 66m

3. 8.1m

4. 8.8m

8.8m

The current definition of the standard meter of length is based on

1. the distance between the earth's equator and north pole.

2. the distance between the earth and the sun.

3. the distance traveled by light in a vacuum.

4. the length of a particular object kept in France.

Three

If the eastward component of vector A is equal to the westward component of vector B and their northward components are equal. Which one of the following statements about these two vectors is correct?

1. The magnitude of vector A is twice the magnitude of vector B.

2. Vector A is perpendicular to vector B .

3. Vector A is parallel to vector B

4. Vectors A and B point in opposite directions.

5. The magnitude of vector A is equal to the magnitude of vector B.

Five

Two bodies P and Q on a smooth horizontal surface are connected by a light cord. The mass of P is greater than that of Q. A horizontal force F (of magnitude F) is applied to Q as shown in the figure, accelerating the bodies to the right. The magnitude of the force exerted by the connecting cord on body P will be

1. less than F but not zero.

2. equal to F.

3. zero.

4. greater than F.

One

Which of the following statements is true about the motion of an object during a period of time in which the total force acting on the object is constant?

1. The direction of the velocity changes if the force is not parallel to the velocity.

2. The speed of the object is proportional to the time the force has acted.

3. The acceleration of the object increases proportional to the time the force has acted.

4. The speed of the object remains constant.

5. The direction of the velocity of the object remains constant.

1.

Two weights (bottom weight 100N and top weight 25N) are pulled connected by a massless wire and pulled upward at constant speed 1.5m/s by a vertical pull P. The tension in the wire is T. Which one of the following relationships between P and T must be true?

1. P = T + 100 N

2. T>P

3. P + T = 125 N

4. T = P

5. P = T + 25 N

Five

The components of vector A are Ax = +2.2 and Ay = -6.9, and the components of vector B are given are Bx = -6.1 and By = -2.2. What is the magnitude of the vector B - À?

A) 0.76

B) 6.1

C) 9.5

D) 91

E) 9.9

C)

Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s. Neither person experiences any significant air resistance. Compare the time it takes each of them to reach the lake below.

1. Tom reaches the surface of the lake first.

2. Alice and Tom will reach the surface of the lake at the same time.

3. Alice reaches the surface of the lake first.

Two

If A and B are nonzero vectors for which ÀxB=0, it must follow that…

A) AxB = AB

B)Ả x B = 0.

C) A is parallel to B.

D) AxB = 1

A)

The speed of a wave pulse on a string depends on the tension, F, in the string and the mass per unit length, u, of the string. Tension has SI units of kg • m • s^-2 and the mass per unit length has to? SI units of kg • m-1. What combination of F and must the speed of the wave be proportional to?

A）Square root of (F/ų)

B) F/ų

C) ų/F

D) square root of (ųF)

E) square root of (ų/F)

B)

A string is attached to the rear-view mirror of a car. A ball is hanging at the other end of the string. The car is driving around in a circle, at a constant speed. Which of the following lists gives all of the forces directly acting on the ball?

1. tension and gravity

2. tension

3. tension, gravity, and the centripetal force

4. tension, gravity, the centripetal force, and friction

1.

What is the magnitude of A + B + C, where A =1.00î + 4.00j -1.00k, B = 3.00î - 1.00j - 4.00k and C = -1.00î + 1.00 3j?

A) 10.76

B) 6.78

C) 2.00

D) 7.07

E) 8.12

D)

When a parachutist jumps from an airplane, he eventually reaches a constant speed, called the terminal speed. Once he has reached terminal speed

1. his speed is equal to 8.

2. the force of air drag on him is equal to g.

3. his acceleration is equal to g.

4. the force of air drag on him is equal to his weight.

5. the force of air drag on him is equal to zero.

4.

Two particles, A and B, are in uniform circular motion about a common center. The acceleration of particle A is 8.5 times that of particle B. The period of particle B is 2.0 times the period of particle A. The ratio of the radius of the motion of particle A to that of particle B is closest to

1. rA/rB = 17.

2. rA/rB = 18.

3. rA/rB = 0.24.

4. rA/r = 4.3.

5. rA/rB = 2.1.

5.

Jan and Len throw identical rocks off a tall building at the same time. The ground near the building is flat. Jan throws her rock straight downward. Len throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30°. Len throws the rock with a speed twice that of Jan's rock. If air resistance is negligible, which rock hits the ground first?

1. Len's rock hits first.

2. Jan's rock hits first.

3. They hit at the same time.

4. It is impossible to know from the information given.

3.

A box of mass m is pulled with a constant acceleration a along a horizontal frictionless floor by a wire that makes an angle of 15° above the horizontal. If T is the tension in this wire, then

A) T < ma.

B) T > ma.

С) T= ma

B)

Suppose the force of the air drag on an object is proportional to the speed of the object and in the direction opposite the object's velocity. If you throw an object upward, the magnitude of its acceleration is greatest

1. right after the object is released

2. at the top of its trajectory.

3. The acceleration of the object is the same throughout the entire trajectory.

1.

An object is moving forward with a constant velocity. Which statement about this object MUST be true?

1. The acceleration of the object is in the forward direction.

2. The net force on the object is zero.

3. The net force on the object is in the forward direction.

4. No forces are acting on the object.

2.

The magnitude of a vector can never be less than the magnitude of one of its components.

A) False

B) True

B)

A hockey puck slides off the edge of a table with an initial velocity of 28.0 m/s. and experiences no air resistance. The height of the tabletop above the ground is 2.00 m. What is the angle below the horizontal of the velocity of the puck just before it hits the ground?

A） 77.2°

B) 12.6°

C) 31.8°

D) 72.6°

E) 12.80

B)

The current definition of the standard second of time is based on

1. the oscillation of a particular pendulum kept in France.

2. the duration of one year.

3. the earth's rotation rate.

4. the frequency of radiation emitted by cesium atoms.

4.

A 60.0-kg person rides in an elevator while standing on a scale. The scale reads 400 N. The acceleration of the elevator is closest to

1. zero.

2. 9.80 m/s2 downward.

3. 3.13 m/s downward.

4. 6.67 m/s2 downward.

5. 6.67 m/s upward.

3.

32) A stalled car is being pushed up a hill at constant velocity by three people. The net force on the car is…

1. up the hill and greater than the weight of the car.

2. down the hill and equal to the weight of the car.

3. down the hill and greater than the weight of the car.

4. zero.

5. up the hill and equal to the weight of the car.

4.

Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s. Neither person experiences any significant air resistance. Just as they reach the lake below

1. the speed of Alice will always be 25 m/s larger than that of Tom.

2. the speed of Tom will always be 9.8 m/s larger than that of Alice.

3. the splashdown speed of Alice is larger than that of Tom.

4. they will both have the same speed.

5. the speed of Alice is larger than that of Tom.

5.

An object is moving to the right, and experiencing a net force that is directed to the right. The magnitude of the force is decreasing with time. The speed of the object is

A) decreasing.

B) constant in time.

C) increasing.

C)

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

1. be over the package.

2. depend of the speed of the plane when the package was released.

3. be in front of the package.

4. be behind the package.

1.

For general projectile motion, when the projectile is at the highest point of its trajectory

1. its velocity and acceleration are both zero.

2. its acceleration is zero.

3. its velocity is perpendicular to the acceleration.

4. the horizontal component of its velocity is zero.

5. the horizontal and vertical components of its velocity are zero.

3.

While an object is in projectile motion (with upward being positive) with no air resistance

1. the vertical component of both its velocity and its acceleration remain constant.

2. the horizontal component of its velocity remains constant and the vertical component of its acceleration is equal to zero.

3. the horizontal component of its velocity remains constant and the horizontal component of its acceleration is equal to -g.

4. the vertical component of its velocity remains constant and the vertical component of its acceleration is equal to -g.

5. the horizontal component of its velocity remains constant and the vertical component of its acceleration is equal to -8.

5.

Under what condition is | A - B 1 = A + B?

A) Vectors A and B are in opposite directions.

B) Vectors A and B are in perpendicular directions.→

C) The magnitude of vector B is zero.

D) Vectors A and B are in the same direction.

E) The statement is never true.

A)

A cart is moving with a constant horizontal velocity of 5.00 m/s. A small pebble is launched from the front of the cart with a velocity of 8.00 m/s at 60.0° above the horizontal as measured relative to the cart (see figure) and experiences no significant air resistance. Just as the pebble returns to the level from which it was launched, its distance from the front of the cart is closest to

A) 2.83 m.

B) 11.3 m.

C) 9.19 m.

D 4.60 m.

E) 5.66 m.

E)

A dog is standing in the bed of a pickup truck. The bed is coated with ice, causing the force of friction between the dog and the truck to be zero. The truck is initially at rest, and then accelerates to the right, moving along a flat road. As seen from a stationary observer (watching the truck move to the right), the dog

1. does not move left or right, but the back of the truck moves towards the dog.

2. moves to the right, but not as quickly as the truck is moving to the right, causing it to slide towards the back of the truck.

3. moves to the left, as the truck moves to the right, causing the dog to slide towards the back of the truck.

4. moves to the right at the same rate as the truck, so it doesn't slide.

A)