physics

A 30-kg girl and a 25-kg boy face each other on friction-free roller blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girl's speed is

0.83 m/s.

Practice entering numbers that include a power of 10 by entering the diameter of a hydrogen atom in its ground state, dH=1.06×10−10m, into the answer box.

1.06x10^-10m

How much speed does a freely falling object gain during each second of fall? Assume that the falling occurs near the Earth's surface and neglect the air drag.

10 m/s

A machine puts out 100 W of power for every 1000 W put into it. The efficiency of the machine is

10 percent.

A gun with a muzzle velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, where will the bullet be 1 s later?

100 m downrange

A pulley system raises a 1000-N load with 100 N of input force. The efficiency of the system is

1000 percent.

A ball is moving at 4 m/s and has a momentum of 48 kg×m/s. What is the ball's mass?

12 kg

A TV set is pushed a distance of 2 m with a force of 20 N that is in the same direction as the set moves. How much work is done on the set?

40 J

A projectile is launched vertically at 50 m/s. If air resistance is negligible, its speed upon returning to its starting point is

50 m/s.

In raising a 5000-N piano with a pulley system, it is noted that for every 1 m of rope pulled down, the piano rises 0.1 m. Ideally, this means the force needed to lift it is about

500 N.

Throw an object at an angle upward. With no gravity it will follow a straight-line path. But because of gravity, at the end of 1 s, it is

5m

A 5000-kg freight car runs into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg car?

6 m/s

You've just solved a problem and the answer is the mass of an electron, me=9.11×10−31 kilograms me = 9.11×10−31kilograms. How would you enter this number into the answer box?

9.11×10^−31

Rank from greatest to least their orbital speeds.

A, B, C

Which of the following describes a growth mindset, as opposed to a fixed mindset?

All of the above

For the astronauts inside the orbiting space shuttle, there is no force of Earth's gravity acting on them. This statement is

Always false

How do students with a growth mindset see their mistakes?

As opportunities to learn and improve their brain

The planet and its moon gravitationally attract each other. Rank the forces of attraction between each pair from greatest to least.

B and C are the same and then its A,D,

Rank the average gravitational forces from greatest to least between (a) the Sun and Mars, (b) the Sun and the Moon, and (c) the Sun and Earth.

C, B, A

Rank from greatest to least their times to orbit Earth.

C,B,A

What is neuroplasticity?

The ability to make new and stronger connections between the neurons in our brain as we learn

What is the effect of air drag on the height and range of batted baseballs?

The effect of air drag is that both range and height are decreased.

With no air drag, what happens to the horizontal component for the ball?

The horizontal component of the ball's velocity remains the same.

What is the source of energy that powers a hydroelectric power plant?

The sunlight that evaporated water that eventually falls as rain and fills the reservoir.

You are starting a new item and after reading the first part you realize you have no idea how to go about answering it. What should you do?

Use the available hints.

Can a machine multiply input distance?

Yes

Can a machine multiply input force?

Yes

Who could lean the farthest over a cliff without falling?

a little girl wearing heavy boots

Without air resistance, a projectile fired horizontally at 8 km/s from atop a mountain will

all of the above

A bullet fired from a rifle begins to fall

as soon as it leaves the barrel

You're driving down the highway and a bug spatters on your windshield. Which undergoes the greater change in momentum?

both the same

When a rifle is fired, it recoils so both the bullet and rifle are set in motion. The rifle and bullet ideally acquire equal

but opposite amounts of momentum.

A cannon recoils from firing a cannonball. The speed of the cannon's recoil is small because the

cannon has more mass than the ball.

What does "centripetal" mean?

center seeking

The power expended when a barbell is raised 2.0 m in 2 s is

dependent on the mass of the barbell.

The force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gases.

Where is your gravity detector?

inside your ear

A "weightless" astronaut in an orbiting shuttle is

like the shuttle, pulled by Earth's gravitation.

An Earth satellite is in an elliptical orbit. The satellite travels fastest when it is

nearest the Earth.

Can a machine multiply input energy?

no

Roll a bowling ball off the edge of a table. As it falls, its horizontal component of motion

remains constant

A projectile is fired vertically from the surface of Earth at 8 km/s. The projectile will

rise and fall back to the Earthʹs surface

If you push an object with twice the work input for twice the time, your power input is

the same amount as for half the work in half the time.

A ball is thrown upward and caught when it comes back down. Neglecting air resistance, the speed with which it is caught is

the same as the speed it had when thrown upward.

An Earth satellite is simply a projectile freely falling around the Earth.

true

If you push an object twice as far while applying the same force, you do

twice as much work

Drag the foods into the appropriate bins. Fruits should be placed in the left bin. Vegetables should be placed in the right bin.

Fruits- Apple, Avocado, Banana, tomato Vegetables- Carrot, Potato

Which is NOT an element in developing expertise in a field?

Giving up

Is it possible to design a machine that has an efficiency greater than 100%?

No because a machine that has an efficiency greater than 100% outputs more energy than it uses, therefore, the machine creates additional energy. It violates the law of energy conservation.

How do you develop a growth mindset and embrace your mistakes?

Question what went wrong and fix the problem in a new strategy

If you are asked to provide a set of two or more numeric answers, separate them with commas. For example, to provide the year that Sputnik (the first satellite to be sent into orbit around the Earth) was launched and the year humans first walked on the Moon, you would enter 1957,1969 in the answer box. A rectangle has a length of 5.50 m and a width of 12.0 m. What are the perimeter and area of this rectangle?

35.0,66.0 m m , m^2

When entering large numbers in the answer box, you may decide whether or not to use commas. For example, you may enter either 1276400 or 1,276,400 for the number 1,276,400. Answer the following question by typing the numeric answer into the answer box. What is the sum of 9260 and 3240?

12500

A friend in your class tells you that she never uses hints when doing her Mastering homework. She says that she finds the hints helpful, but when the hint asks another question it increases the chance that her score on the problem will go down. She feels like it isn't worth the risk.You reassure her that there is nothing to fear about opening a hint that asks a question. Which of the following are good reasons for your friend not to worry?

Correct Answers Are: The only way to lose additional partial credit on a hint is by using the "Request Answer" button or entering incorrect answers. Leaving the question blank will not cost you any credit. Getting the correct answer to the question in a hint actually gives you some partial credit, even if you still can't answer the original question. As an incentive for thinking hard about the problem, your instructor may choose to apply a small hint penalty, but this penalty is the same whether the hint simply gives information or asks another question.

You have been working on an item for a while and after a few missteps you've come up with an answer. However, there is one particular thing that you're not 100% sure of. What should you do?

Correct Answers Are: Return to the question after you've spoken with an instructor or classmate. Submit your answer and then adjust it according to any feedback you receive. Check for any hints that address the part of the calculation you're unsure about.

What is the law of energy conservation?

In the absence of external work input or output, the energy of a system remains unchanged. Energy cannot be created or destroyed.

Why is the word "yet" powerful in developing a growth mindset?

It encourages you to continue along your learning journey, as you have not yet reached the final destination.

What happens to the vertical component of its velocity as the ball rises?

The vertical component of the ball's velocity decreases.

How do people with a growth mindset view and respond to challenges?

They see challenges as opportunities to learn and push their abilities.

A 1000-kg car and a 2000-kg car are hoisted the same distance in a gas station. Raising the more massive car requires

twice as much work.