Total Physics Midterm

How much work would a child do while pulling a wagon a distance of 4.3 m with a force of 22 N?

95 J

Which of the following graphs represent an object at rest?

A

The slope of a position vs. time graph gives

velocity

If you run a complete loop around an outdoor track of length 400 m in 100 s, what is your average speed and velocity?

4 m/s, 0 m/s

An airplane increases its speed at the average rate of 15 m/s². How much time does it take to increase its speed from 100 m/s to 160 m/s?

4.0 s

Add 1299 g and 45.1 kg and express your answer in milligrams (mg) to the correct number of significant figures. *

4.64 x 10^7 mg

If a car accelerates at a uniform 4.0 m/s², how long will it take to reach a speed of 22.22 m/s, starting from rest?

5.56 s

A reasonable estimate for the mass of a typical female college student is *

50 kg

Paul pulls his little sister Sarah along the horizontal ground in a wagon. He exerts a force of 60.0 N at and angle of 37.0 degrees above the horizontal. If he pulls her a distance of 12.0 m, how much work does Paul do?

575 J

How many significant figures are in the number 120.070 *

6

6. An astronaut weighs 99 N on the Moon, where the acceleration of gravity is 1.62 m/s². How much does she weigh on Earth? *

600 N

3. A truck is using a hook to tow a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is 6000 N, the the force exerted by the car on the truck is *

6000 N

How fast must a 6.0 Kg cat run to have a Kinetic Energy of 150 J?

7 m/s

What is the sum of 1.53+2.786+3.3 expressed to the correct number of significant figures? *

7.6

a ball is thrown downward from the top of a building with an initial speed of 25 m/s. It strikes the ground 2.0 s later. How high is the building, assuming negligible air resistance?

70m

If you are driving 72 km/h along a straight road and you look to the side for 4.0 s, how far do you travel during this inattentive period?

80m

A motorist travels for 3.0 h at 80 km/h and 2.0 h at 100 km/h. What is her average speed for the trip?

88 km/h

The graph in the figure shows the position of a particle as it travels along the x-axis. At what value of t is the speed of the particle equal to 0 m/s?

3s

14. A hunter points a rifle horizontally and holds it 3.30 m above the ground. The bullet leaves the barrel at 325 m/s and experiences no significant air resistance. The acceleration due to gravity is 9.8 m/s² at this location. How long does it take for the bullet to strike the ground? *

0.821 s

The figure shows a graph of the velocity of an object as a function of time. What is the acceleration of the object at 5 s?

-10 m/s^2

The figure shows a graph of the position of a moving object as a function of time. What is the velocity of the object at t=5.5 s

-40 m/s

The figure shows a graph of the position of a moving object as a function of time. What is the velocity of the object at t=4.0 s

0 m/s

12. An ornament of mass 40.0 g is attached to a vertical ideal spring with a spring constant of 20.0 N/m. The ornament is then lowered very slowly until the spring stops stretching. How much does the spring stretch? (watch units) *

0.0196 m

A volume of 100 mL is equivalent to which one of the following volumes? *

0.1 L

10. A 50.0 kg crate is being pulled along a horizontal smooth surface. The pulling force is 10.0 N and is directed 20.0° above the horizontal. What is the magnitude of the acceleration of the crate? *

0.188 m/s²

13. A cat leaps to try to catch a bird. If the cat's jump was at 60° off the ground and its initial velocity was 2.74 m/s, what is the highest point of its trajectory, neglecting air resistance? *

0.29 m

9. A 45.0 kg person steps on a scale in an elevator. The scale reads 460 N. What is the magnitude of the acceleration of the elevator? *

0.422 m/s²

The graph in the figure shows the position of a particle as it travels along the x-axis. What is the magnitude of the average velocity of the particle between t=1.0 s and t=4.0 s?

0.67 m/s

The graph in the figure shows the position of a particle as it travels along the x-axis. What is the magnitude of the average speed of the particle between t=1.0 s and t=4.0 s?

1.3 m/s

Which one of the following numbers is equivalent to the number 0.0001776? *

1.776 x 10^-4

10. The x and y components of a vector in the horizontal plane are 8 m and 6 m respectively. What is the magnitude of this vector? *

10 m

The figure shows a graph of the position of a moving object as a function of time. What is the velocity of the object at t=1.0 s

10 m/s

If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery. What distance have you traveled?

10.50 km

How high a hill would a 75 Kg hiker have to climb to increase her gravitational potential energy by 10,000 J?

13.6 m

A car is moving with a speed of 32 m/s. The driver sees an accident ahead and slams on the brakes, causing the car to slow down with a uniform acceleration of magnitude 3.50 m/s². How far does the car travel after the driver puts on the brakes until it comes to a complete stop?

146m

A child pulls on a wagon with a force of 75 N. If the wagon moves 42 m in 186 s, what is the average power delivered by the child?

17 W

A reasonable height of an ordinary adult male is *

170 cm

How many significant figures are in the number 0.010 *

2

In the product AxBxC, A has 5 significant figures, B has 2 significant figures, and C has 3 significant figures. How many significant figures does the product have? *

2

In the sum A+B+C, A is accurate to 5 decimal places, B is accurate to 2 decimal places, C is accurate to 3 decimal places. What is the correct number of decimal places in the sum? *

2

If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery. What is your displacement?

2.50 km south

Express the sum 1.00 kg + 1531 g + 25400 mg in kilograms with the correct number of significant figures. *

2.56 kg

8. An object that weighs 75 N is pulled on a horizontal surface by a horizontal pull of 50 N to the right. The friction force on this object is 30 N to the left. What is the acceleration of the object? *

2.6 m/s²

12. A girl throws a rock horizontally, with a velocity of 10 m/s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water, assuming negligible air resistance? *

20 m

The figure shows a graph of the position of a moving object as a function of time. What is the velocity of the object at t=2.5 s

20 m/s

Express 50 mi/hr in units of meters per second. (1 mi = 1609 m) *

22 m/s

11. A 50 kg box is being pushed along a horizontal surface. the coefficient of kinetic friction between the box and the ground is 0.35. What horizontal force must be exerted on the box for it to accelerate at 1.2 m/s²? *

230 N

A reasonable estimate for the duration of a typical physics lecture is *

2500 s

An object moves 15.0 m north and then 11.0 m south. Find both the distance it has traveled and the magnitude of its displacement.

26.0 m, 4.0 m

What is the product of 12.56 and 2.12 expressed to the correct number of significant figures? *

26.6

15. A hunter points a rifle horizontally and holds it 3.30 m above the ground. The bullet leaves the barrel at 325 m/s and experiences no significant air resistance. The acceleration due to gravity is 9.8 m/s² at this location. How far horizontally does it travel? *

266.8 m

To determine the height of a bridge above water, a person drops a stone and measures the time it takes for it to hit the water. If the time is 2.3 s, what is the height of the bridge? (Neglect air resistance)

26m

A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 minutes. What was the average speed of the runner in m/s?

3.95 m/s

7. What magnitude net force is required to accelerate a 1200 kg car uniformly from 0 m/s to 27.0 m/s in 10.0 s? *

3240 N

A roller coaster car is moving at 20 m/s at point W, which is 200 m above the ground, on the track shown in the figure. This track is friction free with no appreciable air resistance. What is the speed at point Y, which is 160 m above the ground?

34 m/s

A 1000 Kg car experiences a net force of 9500 N while slowing down from 30 m/s to 15.9 m/s. How far does it travel while slowing down?

34m

11. The x and y components of a vector in the horizontal plane are 8 m and 6 m respectively. What angle does this vector make with the + x-axis? *

36.9

7. In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles. *

They hit at the same time.

An object can have a positive velocity and a negative acceleration at the same time.

True

In the previous graph the cars meet at t=10s.

True

The figure shows a graph of the position of two cars, C and D, as a function of time t. According to the graph, which statement about these cars must be true?

Both cars have the same acceleration.

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.

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

9. Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal: Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements is true about the snowballs as they just reach the ground? *

Both snowballs reach the ground with the same speed.

The metric system is preferred over the British system in science for the following main reason. *

Conversions between metric quantities are especially easy because they are all related by factors of ten.

1. A satellite is in orbit around the earth. Which one feels the greater force. *

Earth and the satellite feel exactly the same force.

If the acceleration of an object is zero, then that object cannot be moving

False

If the velocity of an object is zero at some point, then its acceleration must also be zero at that point.

False

Using dimensional analysis, which one of the following equations is dimensionally correct? In these equations, x has units of meters, t has units of seconds, v has units of meters per second, and a has units of meters per second squares. *

t^2 = x/a

2. A small car and a large SUV are at a stoplight. The car has a mass equal to half that of the SUV, and the SUV can produce a maximum accelerating force equal to twice that of the car. When the light turns green, both drivers push their accelerators to the floor at the same time. Which vehicle pulls ahead of the other vehicle after a few seconds? *

It is a tie.

When multiplying several quantities *

the quantities can have any combination of units.

A truck has four times the mass of a car and is moving with twice the speed of the car. If Kt and Kc refer to the Kinetic Energies of the truck and car respectively, it is correct to say that

Kt = 16Kc

6. For general projectile motion with no air resistance, the vertical component of a projectile's acceleration *

remains a non-zero constant.

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 minutes, while Joel is able to push for 5.0 minutes longer. Compare the work they do on the car.

Neither of them does any work.

A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t=0s. If we take upward as the positive direction, which of the graphs shown below best represents the acceleration of the stone as a function of time?

Option 2

A stone can slide down one of four different frictionless ramps, as shown below. For which ramp will the speed of the ball be the greatest at the bottom?

The speed of the ball will be the same for all ramps.

Suppose that an object travels from one point to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.

The displacement is either less than or equal to the distance traveled.

4. You are standing in a moving bus, facing forward, when you suddenly slide forward as the bus comes to an immediate stop. What force caused you to slide forward? *

There is not a force causing you to slide forward.

An object has a position - time graph that is a straight line with a negative slope. Is the acceleration of this object positive, negative or zero?

Zero

When adding several quantities *

the quantities must all have exactly the same units.

The slope of a velocity v. time graph gives

acceleration

3. If vectors A + B = C and their magnitudes A + B = 0, then vectors A and B are oriented *

antiparallel to each other (in opposite directions).

8. 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 *

be directly over the package.

1. Two vectors have magnitudes of 5.0 m and 7.0 m respectively. If these two vectors are added together, the magnitude of the sum *

could be as small as 2.0 m or as large as 12 m.

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?

exactly g

Jill does twice as much work as Jack does in half the time. Jill's power output is

four times Jack's power output.

4. You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat *

in a general northwesterly direction.

5. For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration *

is always zero.

You drive 6.0 km at 50 km/hr and then another 6.0 km at 90 km/hr. Your average speed over the 12 km drive will be

less than 70 km/hr

5. A person who normally weighs 700 N is riding in an elevator that is moving upward but slowing down at a steady rate. If this person is standing on a bathroom scale inside the elevator, what would the scale read? *

less than 700 N

2. If vectors A + B = C and their magnitudes A + B = C, then vectors A and B are oriented *

parallel to each other (in the same direction).