PHY 265 Exam 1

A Honda Civic Hybrid weighs about 3150 lb. Calculate the weight of the car in Newtons (Note: 0.22 lb = 1N).

W = 1.4x10^4 N

The sketch shows a painter's scaffold in mechanical equilibrium. The person in the middle weighs 540 N, and the tension in each rope is 460 N What is the weight of the scaffold?

W = 380 N

Lucy Lightfoot stands with one foot on one bathroom scale and her other foot on a second bathroom scale. Each scale reads 400 NN . What is Lucy's weight?

W = 800 N

The support force on a 10-N book that rests on a horizontal surface is a. less than 10 N. b. greater than 10 N. c. 10 N. d. dependent on whether the book lies flat or stands upright.

c. 10 N

How does the distance traveled by the ball in the second half second compare with the distance traveled by the ball in the first half second? a. It stays the same. b. It decreases. c. It increases.

c. It increases

If the mass of a sliding block is tripled at the same time that the net force on it is tripled, how does the resulting acceleration compare to the original acceleration? a. It is tripled. b. It is increased nine times. c. It remains the same. d. It is increased six times.

c. It remains the same.

Suppose a monkey weighs 102 NN and the vine supporting her pulls upward with a force of 150 NN. Describe her motion. a. The monkey moves upward with a constant speed while the force acts. b. The monkey moves downward with a constant speed while the force acts. c. The monkey accelerates upward while the force acts. d. The monkey accelerates downward while the force acts.

c. The monkey accelerates upward while the force acts.

Someone standing at the edge of a cliff (as in the figure) throws a ball straight up at a certain speed and another ball straight down at the same initial speed. If air resistance is negligible, which ball will hit the ground below at greater speed? Or will they both hit at the same speed. a. A ball thrown straight down will hit with greater speed. b. A ball throw straight up will hit with greater speed. c. They will hit at the same speed.

c. They will hit at the same speed.

When you simultaneously drop a light tennis ball and a heavy bowling ball, they hit the floor a. with the same force. b. with the same momentum. c. at the same speed. d. all of the above e. none of the above

c. at the same speed

The equilibrium rule F = 0 applies to a. objects or systems at rest. b. objects or systems in uniform motion in a straight line. c. both d. neither

c. both

Does the speedometer on a vehicle show average speed or instantaneous speed? a. average velocity b. average speed c. instantaneous speed d. instantaneous velocity

c. instantaneous speed

Identify the force that propels a rocket into space. a. the reaction force of the air pushing back on the propellant b. the repulsion force from gravity of the Earth on the rocket c. the reaction force of the expelled propellant on the rocket d. the reaction force from the gravity of the Earth on the rocket

c. the reaction force of the expelled propellant on the rocket

What is the Physics Primer? a. A tutorial of the most important physics concepts covered in introductory physics courses. b. A detailed explanation of all of the mathematics you will use in your introcuctory physics course. c. A list of the most important formulas used in introductory physics courses. d. A set of mathematics topics that are relevant to introductory physics courses.

d. A set of mathematics topics that are relevant to introductory physics courses.

What is the acceleration of the ball when it is moving up, when it is at the maximum height, and when it is moving down? (Note: The acceleration graph is shown in red.) a. The acceleration is negative when the ball is moving up, zero at the top, and positive when the ball is moving down. b. The acceleration is positive when the ball is moving up, zero at the top, and negative when the ball is moving down. c. It is always positive. d. It is always negative. d. It is always zero.

d. It is always negative.

Why do we say that velocity is a vector and speed is not? a. Velocity happens in three dimensions, and speed happens in two dimensions. b. Velocity has a vertical component, and speed does not. c. Speed is never zero, and velocity can be zero. d. Velocity includes a direction, and speed does not.

d. Velocity includes a direction, and speed does not.

How can you use the graph of velocity versus time to estimate the acceleration of the ball? a. by estimating the value of the area under the graph b. by estimating the value from the vertical axis of the graph c. by estimating the value from the horizontal axis of the graph d. by estimating the value of the slope of the graph

d. by estimating the value of the slope of the graph

An airplane starting from rest at one end of a runway accelerates uniformly at 4.5 m/s2 for 13 s before takeoff. Find a distance that the plane travels along the runway before takeoff.

d= 380 m

Lillian rides her bicycle along a straight road at average velocity v. Write an equation showing the distance she travels in time t.

d= vt

You would like to know whether silicon will float in mercury and you know that can determine this based on their densities. Unfortunately, you have the density of mercury in units of kilogram/meter^3 and the density of silicon in other units: 2.33 gram/ centimeter^3. You decide to convert the density of silicon into units of kilogram/ meter^3 to perform the comparison. By which combination of conversion factors will you multiply 2.33 gram/ centimeter^3 to perform the unit conversion?

1 kilogram/ 10^3 gram × 1 centimeter/ 10^−2meter × 1 centimeter/ 10^−2 meter × 1 centimeter 10^−2 meter

Suppose a monkey weighs 102 NN and the vine supporting her pulls upward with a force of 150 NN. What is the net force on the monkey?

48 N

A student solving a physics problem for the velocity of an object has applied appropriate physics principles and obtained the expression v= d/t − v0, where d= 35.0 meter d=35.0 meter, t=9.00 second, and v0=3.00 meter/second. What is the velocity v?

8.00 meter/ 9.00 second

When the strong man shown (Figure 1) exerts a downward force of 890 NN on the rope, how much upward force is exerted on the block?

890 N

Find the strength of the net force produced by a 20-NN force and a 8.0-NN force in each of these cases. The two forces act in opposite directions.

F = 12 N

Find the strength of the net force produced by a 20-NN force and a 8.0-NN force in each of these cases. Both forces act in the same direction.

F= 28 N

If you stand next to a wall on a frictionless skateboard and push the wall with a force of 32 N, how hard does the wall push on you?

F= 32 N

Leroy, who has a mass of 90.0 kg , is skateboarding at 8.4 m/s when he smacks into a brick wall and comes to a dead stop in 0.24 s. Find the force of impact.

F= 3200 N

Impulse = change in momentum; Ft=mv When a 7.0-kg cart undergoes a 1.6 m/s increase in speed, what is the impulse on the cart?

Ft = (11 kg x m)/s

Lillian rides her bicycle along a straight road at average velocity v. If Lillian's average speed is 7.1 m/s for a time of 5.8 min, find the distance that she travels.

If Lillian's average speed is 7.1 m/s for a time of 5.8 min, find the distance that she travels.

Finally, what is the numerical value of aa?

a = 4.71 meter/ second^2

In an experiment you are performing, your lab partner has measured the distance a cart has traveled: 28.4inch. You need the distance in units of centimeter and you know the unit equality 1inch=2.54centimeter. By which conversion factor will you multiply 28.4inch in order to perform the unit conversion? a. 2.54 centimeter/ 1 inch b. 2.54 inch / 1 centimeter c. 1 inch / 2.54 centimeter d. 1 centimeter/ 2.54 inch

a. 2.54 centimeter/ 1 inch

What is the acceleration of an object that moves at constant velocity? What is the net force on the object in this case? a. Acceleration is zero; net force is zero. b. Acceleration is greater than zero; net force is zero. c. Acceleration is greater than zero; net force is greater than zero. d. Acceleration is zero; net force is greater than zero.

a. Acceleration is zero; net force is zero.

What is the value of the velocity of the ball when it reaches its maximum height? a. It is always zero. b. It is always negative. c. It is either positive or negative, depending on the initial velocity. d. It is always positive.

a. It is always zero.

Which friend do you agree with, and why? a. The first friend. Whatever push she exerts on the tree, briefly or otherwise, the pushback by the tree will be equal and opposite. That's Newton's 3rd law. b. The second friend. Newton's 3rd law does state that there would be equal and opposite forces, but this technically only applies to a sustained force, not an instantaneous force.

a. The first friend. Whatever push she exerts on the tree, briefly or otherwise, the pushback by the tree will be equal and opposite. That's Newton's 3rd law.

When Dr. Hewitt pulls the tablecloth, why do the items on the tablecloth do what they do? a. Their inertia is sufficient to keep them there. b. Friction with the table is keeping them there. c. Friction with the tablecloth is keeping them there. d. They are attached to the tablecloth.

a. Their inertia is sufficient to keep them there.

Why do the alphabet letters tend to do what they do when you rotate the bowl? a. They have inertia−−the tendency of an object at rest to stay at rest. b. The letters are heavier than the soup, so they cannot move even though the soup moves. c. The soup prevents the letters from moving. d. The sides of the soup bowl prevent the letters from moving.

a. They have inertia−−the tendency of an object at rest to stay at rest.

Why do the clay blobs do what they do when Dr. Hewitt turns around? a. They have inertia−−the tendency of an object at rest to stay at rest. b. Dr. Hewitt is holding them there. c. Friction with the head is keeping them there. d. Dr. Hewitt is turning them back to their original position.

a. They have inertia−−the tendency of an object at rest to stay at rest.

When Dr. Hewitt pulls the tablecloth, what happens to the items on the tablecloth? a. They tend to stay where they were. b. They move vertically upward. c. They move horizontally in the opposite direction from the tablecloth. d. They move horizontally in the same direction as the tablecloth.

a. They tend to stay where they were.

Some alphabet letters are floating in a bowl of soup. You want to move a letter that is far away from you closer to you. How could you rotate the bowl to do that? a. Unfortunately, neither rotating the bowl clockwise nor rotating it counterclockwise will work. b. Rotate the bowl counterclockwise. c. Rotate the bowl either clockwise or counterclockwise, depending on where the letter is located. d. Rotate the bowl clockwise.

a. Unfortunately, neither rotating the bowl clockwise nor rotating it counterclockwise will work.

Distinguish between velocity and acceleration. a. Velocity is the change in your position in a time interval; acceleration is the change in velocity in a time interval. b. Acceleration is the change in your position in a time interval; velocity is the change in speed in a time interval. c. Velocity and acceleration are the same. d. Very fast velocity is known as acceleration.

a. Velocity is the change in your position in a time interval; acceleration is the change in velocity in a time interval.

You tell your friend about the neat tablecloth trick that Dr. Hewitt demonstrated. Your friend tries to repeat this trick at home and later complains to you that it failed. Which of the following is most likely the reason that it failed? a. Your friend pulled the tablecloth too slowly. b. Your friend pulled the tablecloth too quickly. c. The items placed on the tablecloth were too light. d. Your friend is too clumsy.

a. Your friend pulled the tablecloth too slowly.

In general, the friction forces between one object and another act a. in opposite directions. b. in the same direction. c. at right angles to each other. d. none of the above

a. in opposite directions.

A student solving for the acceleration of an object has applied appropriate physics principles and obtained the expression a = a1 + F/m where a1=3.00 meter/second2, F=12.0 kilogram⋅meter/second2 and m=7.00 kilogram. First, which of the following is the correct step for obtaining a common denominator for the two fractions in the expression in solving for a?

a= (m/m⋅a1/1)+(1/1⋅F/m)

Part complete If your mass is 88 kg , find your acceleration.

a= 0.36 m/s^2

Sophia exerts a steady 36-N horizontal force on a 7.8-kg box resting on a lab bench. The box slides against a horizontal friction force of 27 N. Find the box acceleration.

a= 1.2 m/s^2

If the cart's mass is 4.8 kg , the applied force is 13.0 N , and the friction force is 6.2 N , find the cart's acceleration.

a= 1.4 m/s^2

Acceleration = change of velocity/ time interval Find the acceleration of a car that can go from rest to 150 km/h in 15 s .

a= 2.8 m/s^2

A business jet of mass 22000 kg takes off when the thrust for each of two engines is 38000 N. Find its acceleration

a= 3.5 m/s^2

Leroy, who has a mass of 90.0 kg , is skateboarding at 8.4 m/s when he smacks into a brick wall and comes to a dead stop in 0.24 s. Find his deceleration

a= 35 m/s^2

Acceleration = change of velocity/ time interval Find the acceleration of a hamster when it increases its velocity from rest to 8.0 m /s in 2.0 s.

a= 4.0 m/s^2

Find the acceleration for a ball that starts from rest, rolls down a ramp, and gains a speed of 38 m/s in 4.8 s .

a= 7.9 m/s^2

A force F acts in the forward direction on a cart of mass m. A friction force f opposes this motion. Use Newton's second law and express the acceleration of the cart. Express in terms if F,f,m

a= F-f/m

Next, based on the correct answer from Part A, which of the following is the correct symbolic expression for a?

a= ma1+F/m

Would acceleration be greater or less if the ramp were a bit less steep? a. Acceleration would be greater on a less-steep ramp. b. Acceleration would be less-steep ramp.

b. Acceleration would be less-steep ramp.

Why does the distance traveled by the ball in each half second after it is released change in the way in which it does? a. The incline plane pushes up on the ball, so it accelerates down at a steady rate. b. Gravity is pulling down on the ball, so it accelerates down at a steady rate. c. Gravity is pulling down on the ball, so it moves down at a steady speed.

b. Gravity is pulling down on the ball, so it accelerates down at a steady rate.

Dr. Hewitt has clay "blobs" hanging on either side of his head in this video. When he turns around, what happens to the blobs? a. The blobs fall off Dr. Hewitt's head. b. The blobs tend to stay where they were. c. The blobs turn around in the same direction as Dr. Hewitt. d. The blobs turn around in the opposite direction from Dr. Hewitt.

b. The blobs tend to stay where they were.

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater a. speed. b. momentum. c. acceleration. d. all of the above e. none of the above

b. momentum

Consider the video demonstration that you just watched. Which of the following changes would make it more likely for the ball to hit both the white can and the green can? a. Roll the ball faster. b. Use a ball that is heavier than the original ball. c. Roll the ball slower. d. Use a ball that is lighter than the original ball, but still heavier than an empty can. e. None of the above

e. None of the above

A 5.0-kg bag of groceries is tossed onto a table at 2.6 m/s and slides to a stop in 2.4 s. Modify the equation F(change in time)=(change in)(mv) to find the force of friction

f = 5.4 N

You have negotiated with the Omicronians for a base on the planet Omicron Persei 7. The architects working with you to plan the base need to know the acceleration of a freely falling object at the surface of the planet in order to adequately design the structures. The Omicronians have told you that the value is gOP7=7.29gOP7=7.29 flurg grom^2, but your architects use the units meter second^2, and from your previous experience you know that both the Omicronians and your architects are terrible at unit conversion. Thus, it's up to you to do the unit conversion. Fortunately, you know the unit equality relationships: 5.24 flurg = 1 meter and 1 grom = 0.493 second. What is the value of gOP7 in the units your architects will use, in meter/second^2?

gOP7 = 5.72 meter/ second^2

Determine the values of m and n when the following average magnetic field strength of the Earth is written in scientific notation: 0.0000451 T

m, n = 4.51, -5

Determine the values of m and n when the following mass of the Earth is written in scientific notation: 5,970,000,000,000,000,000,000,000 kg

m, n = 5.97, 24

Determine the values of m and n when the following average distance from the Sun to the Earth is written in scientific notation: 150,000,000,000 mm.

m,n = 1.5, 11

Determine the values of m and n when the following charge of a proton is written in scientific notation: 0.000000000000000000160 C.

m,n = 1.60, -19

The mass of a high speed train is 4.5×105 kg, and it is traveling forward at a velocity of 8.3×101 m/s. Given that momentum equals mass times velocity, determine the values of mm and n when the momentum of the train (in kg⋅m/s) is written in scientific notation.

m,n = 3.7,7

Given that average speed is distance traveled divided by time, determine the values of m and n when the time it takes a beam of light to get from the Sun to the Earth (in s) is written in scientific notation. Note: the speed of light is approximately 3.0×108 m/s.

m,n = 5.0, 2

A Honda Civic Hybrid weighs about 3150 lb. Calculate the mass of the car in kilograms. (NoteL 1kg on Earth's surface has a weight of 10N).

m= 1400 kg

Jeannie Beanie (mass 40 kg), standing on slippery ice, catches her leaping dog, Daisy (mass 14 kg), who leapt into her arms after running across an adjacent field at 2.0 m/s. Use the conservation of momentum to find the speed of Jeannie and her dog after the catch.

v= 0.52 m/s

A 5.4-kg fish swimming at 0.70 m/s swallows an absent-minded 1.2-kg fish swimming toward it at a velocity that brings both fish to a halt. Find the speed of the smaller fish before lunch.

v= 3.2 m/s

An airplane starting from rest at one end of a runway accelerates uniformly at 4.5 m/s2 for 13 s before takeoff. What is its speed of takeoff?

v= 59 m/s