Physics 1

An object is under the influence of a force as represented by the force vs. position graph in Figure 7-5. What is the work done as the object moves from 4 m to 6 m?

20 J

A projectile is launched with an initial velocity of 80 m/s at an angle of 30° above the horizontal. Neglecting air resistance, what is horizontal component of the projectile's acceleration?

40 m/s^2

What is the conversion factor between km/h and m/s?

2.78 × 10^-1 m/s

A projectile is shot horizontally at 23.4 m/s from the roof of a building 55.0 m tall. (a) Determine the time necessary for the projectile to reach the ground below. (b) Determine the distance from the base of the building that the projectile lands. (c) Determine the horizontal and vertical components of the velocity just before the projectile reaches the ground.

(a) 3.35 s (b) 78.4 m (c) vhorizontal = 23.4 m/s, vvertical = 32.8 m/s

An object of mass 4.00 kg is sitting at the top of an inclined plane of height h and angle O with the horizontal. The object slides down the inclined plane and right before it reaches the bottom of the plane, it has speed of 16.0 m/s. Neglect friction and use g = 10.0 m/s^2. (a) What is the height of the inclined plane? (b) If the height of the inclined plane is raised to 15.0 m, what is the speed of the object right before it reaches the bottom of the inclined plane?

(a) 12.8 m (b) 17.3 m/s

A horizontal force of 40 N pushes an object of mass 5.0 kg up an inclined plane through a distance of 1.6 m measured along the plane. The plane is inclined at an angle of 30° to the horizontal. Neglect friction and use g = 10 m/s^2. (a) What is the work done by the horizontal force on the object? (b) What is the work done by the net force on the object? (c) What is the work done by the normal force on the object?

(a) 55 J (b) 15 J (c) 0 J

Vector A is 5.5 cm long and points along the x-axis. Vector B is 7.5 cm long and points at +30° above the negative x-axis. (a) Determine the x- and y-components of Vector A. (b) Determine the x- and y-components of Vector B. (c) Determine the sum of these two vectors in terms of components. (d) Determine the sum of these two vectors in terms of magnitude and direction.

(a) Ax = 5.5 cm, Ay = 0 (b) Bx = -6.5 cm, By = 3.8 cm (c) Rx = -1.0 cm, Ry = 3.8 cm (d) 3.9 cm at 75° above -x-axis

A ball is thrown straight up with a speed of 30 m/s. (a.) How long does it take the ball to reach the maximum height? (b.) What is the maximum height reached by the ball? (c.) What is its speed after 4.2 s?

(a.) 3.1 s (b.) 46 m (c.) 11 m/s

A person applies a constant force of 20 N to a rock of mass 1000 kg, for a total of 20 seconds. What is the work done by this person if the rock does not move at all by this applied force?

0 J

A 2-kg ball is moving with a constant speed of 5 m/s in a horizontal circle whose radius is 50 cm. What is the magnitude of the net force on the ball?

100 N

How many cm^2 equal a m^2?

10^4

A net force of 450 N applied to a car results in the car accelerating at 0.360 m/s2. What is the mass of the car?

1250 kg

A 55.0-kg box rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.300. What horizontal force must be applied to the box for it to start sliding along the surface?

162 N

A boy jumps at a speed of 20.0 m/s at an angle of 25.0° above the horizontal. What is the horizontal component of the boy's velocity?

18.1 m/s

Refer to Figure 6-11. Block A has a mass of 3.00 kg and rests on a smooth table and is connected to block B, which has a mass of 2.00 kg, after passing over an ideal pulley, as shown. Block B is released from rest. What is the acceleration of the masses?

3.92 m/s^2

What average net force is required to accelerate a car with a mass of 1200 kg from 0 to 27.0 m/s in 10.0 s?

3240 N

A player throws a football 74.0 m at 61.0° north of west. The westward component of the displacement of the football thrown is given by?

35.9 m

A 500-kg cannon fires a 4.0-kg projectile with a velocity of 500 m/s relative to the ground. What is the recoil speed of the cannon?

4.0 m/s

Refer to Figure 6-11. Block A has a mass of 2.80 kg and rests on a smooth table and is connected to block B, which has a mass of 2.20 kg, after passing over an ideal pulley, as shown. Block B is released from rest. What is the acceleration of the masses?

4.32 m/s^2

A batter hits a 0.140-kg baseball that was approaching him at 30.0 m/s and, as a result, the ball leaves the bat at 40.0 m/s in the direction of the pitcher. The ball remains in contact with the bat for 2.0 ms. What is the average force exerted by the bat?

4900 N

Vector M = 4.00 m points eastward and vector N = 3.00 m points southward. The resultant vector M + N is given by?

5.00 m at an angle 36.9° south of east.

A 2-kg ball is moving with a constant speed of 5 m/s in a horizontal circle whose radius is 50 cm. What is the acceleration of the ball?

50 m/s^2

What is the magnitude of the momentum of a 0.140 kg baseball traveling at 45.0 m/s?

6.30 kg·m/s

An object of mass = 2 kg is pulled by a constant force F = 4 N for a horizontal distance of 2 m. (Refer to Figure 7-3.) What is the work done along the +x-axis? Neglect friction.

7 J

A batter applies an average force of 8000 N to a baseball for 1.10 ms. What is the magnitude of the impulse delivered to the baseball?

8.80 Ns

Refer to Figure 8-5. What is the kinetic energy of the bead at point A?

A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s^2. 0 J

Refer to Figure 8-5. What is the kinetic energy of the bead at point B?

A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s^2. 2.0 x 10^-2 J

Refer to Figure 8-5. What is the potential energy of the bead at point A?

A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s^2. 2.0 x 10^-2 J

Refer to Figure 8-5. What is the speed of the bead at point B?

A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s^2. 4.5 m/s

Refer to Figure 3-1. The components of vectors A and B are?

Ax = A cos 0° Bx = -B cos 60° Ay = A cos 90° By = B cos 30°

Suppose that a car traveling to the East (+x direction) begins to slow down as it approaches a traffic light. Make a statement concerning its acceleration.

The car is decelerating, and its acceleration is negative.

You and your friend 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 (U) of you and your friend, after you both reach the top.

Both of you have the same amount of potential energy.

Four students measure the mass of an object, each using a different scale. They record their results as follows: Which student used the least precise scale?

C

A body moving with constant speed cannot be accelerating.

FALSE

The acceleration of an object does not have to be in the same direction as the net force applied to it.

FALSE

The impulse delivered to an object is equal to the change in the object's velocity.

FALSE

Work is a vector quantity.

FALSE

A monkey is sitting at the top of a tree 20 m high from the ground level. A person standing on the ground wants to feed the monkey. He uses a bow and arrow to launch the food to the monkey. If the person knows that the monkey is going to drop from the tree at the same instant that the person launches the food, how should the person aim the arrow containing the food?

He should aim it at the monkey.

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below.

James and John will reach the surface of the lake at the same time.

An acorn falls from a tree. Compare its kinetic energy K, to its potential energy U.

K increases and U decreases

King Kong falls from the top of the Empire State Building, through the air (air friction is present), to the ground below. How does his kinetic energy (K) just before striking the ground compare to his potential energy (U) at the top of the building?

K is less than U

A block of mass M slides down a frictionless plane inclined at an angle O with the horizontal. The normal reaction force exerted by the plane on the block is?

Mg cos O

In Figure 6-1, the block of mass m is at rest on an inclined plane that makes an angle O with the horizontal. The force of static friction f must be such that?

f = mg sinO

An artillery shell explodes in midair and breaks up into many fragments. Which of the following statements are true regarding conditions immediately before and immediately after the explosion: I. The total momentum of the fragments is equal to the original momentum of the shell. II. The total kinetic energy of the fragments is equal to the original kinetic energy of the shell.

Statement I only

A particle that has zero momentum must also have zero kinetic energy.

TRUE

For uniform circular motion, the velocity and acceleration vectors are perpendicular to each other at every point in the path.

TRUE

Force is a vector quantity.

TRUE

Kinetic energy is a scalar quantity.

TRUE

The banking angle for a properly banked curve does not depend on the mass of the car going over it.

TRUE

The coefficient of static friction is always larger than the coefficient of kinetic friction.

TRUE

The force of static friction between two surfaces is independent of the area of contact between the surfaces.

TRUE

The mass of an object is fixed, but its weight varies from location to location.

TRUE

The net force acting on an object is equal to the rate of change of its momentum.

TRUE

Work done by a force on an object can be a positive or a negative quantity.

TRUE

Suppose that an object is moving with a constant velocity. Make a statement concerning its acceleration.

The acceleration must be equal to zero.

A ball rolls off the edge of a table. The horizontal component of the ball's velocity remains constant during its entire trajectory because?

The ball is not acted upon by a force in the horizontal direction.

A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car. Since a lot of damage is done on the car?

The force on the truck is equal to the force on the car.

An object is moving with constant velocity. Which of the following statements is true?

The net force on the object is zero.

Two masses, m1 and m2, are connected to each other as shown in Figure 6-5. Mass m1 slides without friction on the table surface. Both masses have acceleration of magnitude a as shown. How does the tension in the string compare to the weight, m2g, of mass m2?

The tension is smaller than m2g.

A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which statement is correct?

The total momentum both before and after the collision is zero.

At a given instant, the acceleration of a certain particle is zero. This means that?

The velocity is not changing at that instant.

A car travels along east and its velocity decreases. The acceleration of the car is in which of the following directions?

Westward

An object of weight W is in free-fall close to the surface of Earth. What is the force that the object exerts on Earth?

a force equal to W

An object is moving with constant non-zero acceleration in the +x-axis. The position versus time graph of this object is?

a parabolic curve

A vector quantity is defined as?

a quantity that is specified by using both a numerical value and a direction

During the time that the acceleration of a particle is constant, its velocity-vs.-time curve is?

a straight line

If the position versus time graph of an object is a horizontal line, the object is?

at rest

The slope of a line connecting two points on a velocity versus time graph gives?

average acceleration

The slope of a line connecting two points on a position versus time graph gives?

average velocity

Describe the energy of a car driving up a hill.

both kinetic and potential

The metric prefix for one one-hundredth is?

centi

What type of acceleration does an object moving with constant speed in a circular path experience?

centripetal acceleration

For a projectile launched horizontally, the vertical component of a projectile's velocity?

continuously increases

If the net work done on an object is negative, then the object's kinetic energy?

decreases

The area under a curve in a velocity versus time graph gives?

displacement

When adding several quantities, the number of decimal places in the result must always be?

equal to the number of decimal places in the least accurate of the quantities

When multiplying several quantities, the number of significant digits in the result must always be?

equal to the number of significant digits in the least accurate of the quantities

You ride on an elevator that is moving downward with constant speed while standing on a bathroom scale. The reading on the scale is?

equal to your true weight, mg

A golf club hits a golf ball with a force of 2400 N. The golf ball hits the club with a force?

exactly 2400 N

If the net work done on an object is positive, then the object's kinetic energy?

increases

The slope of a tangent line at a given time value on a velocity versus time graph gives?

instantaneous acceleration

The slope of a tangent line at a given time value on a position versus time graph gives?

instantaneous velocity

The total mechanical energy of a system?

is constant, only if conservative forces act

For general projectile motion, the horizontal component of a projectile's acceleration?

is zero

You ride on an elevator that is moving with constant downward acceleration while standing on a bathroom scale. The reading on the scale is?

less than your true weight, mg

The metric prefix for one one-thousandth is?

milli

A ball drops some distance and gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the ball lose?

more than 30 J

In the absence of an external force, a moving object will?

move with constant velocity

You apply the same force to two objects. Object 1 has mass M and object 2 has mass 5M. The acceleration of object 2 is?

one-fifth as that of object 1

When is the average velocity of an object equal to the instantaneous velocity?

only when the velocity is constant

For general projectile motion, the horizontal component of a projectile's velocity?

remains a non-zero constant

For general projectile motion, the vertical component of a projectile's acceleration?

remains a non-zero constant

If you push twice as hard against a stationary brick wall, the amount of work you do?

remains constant at zero

If the net work done on an object is zero, then the object's kinetic energy?

remains the same

Swimmers at a water park have a choice of two frictionless water slides (see Figure 8-2). Although both slides drop over the same height, h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the end of slide 1 compares with v2, the speed of a swimmer reaching the end of slide 2?

v1 = v2

Two identical masses are attached by a light string that passes over a small pulley, as shown in Figure 6-6. The table and the pulley are frictionless. The masses are moving?

with an acceleration less than g

On a force vs. position graph, the area under curve is a representation of?

work

Its more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity, because?

μk < μs