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Physics High School

In which of the following sentences is work used in the scientific sense of the word? A scientist works on an experiment in the laboratory.* B Sam and Rachel pushed, but they could do no work on the car. ????

2 months ago

Solution 1

Guest #6877099

2 months ago

B) obviously. Work in a scientific sense is the ability to make a displacement on an object in this case.

In A) the scientist can work on an experiment as your uncle can work on the field planting tomatos.

📚 Related Questions

Question

According the kinetic theory of matter, which of the following statements is true about matter

Solution 1

Hi

a. the atoms and molecules of a substance are always in motion
b. the higher the temperature of a substance, the faster its particles move
c. more massive particles move more slowly than less massive particles.

these are the main points of kinetic theory of matter.

Kinetic Theory of Matter
The kinetic theory of matter states that all matter is made of small particles that are in random motion and that have space between them. This means that no matter what phase matter is in, it is made of separate, moving particles.
This theory sounds pretty simple, but it actually explains a lot about the physical properties of matter and how it behaves. You might be surprised to learn that the particles of a solid are actually moving, just not enough for you to see. This type of vibrational movement is why a solid won't change shape no matter what kind of container you put it in.
Remember how liquid particles have more energy than solids? The extra energy in this state allows the particles to move around more freely, and they spread out more than those of a solid, putting more space between those particles. This is why a liquid will take the shape of its container up to its surface.
And since gases have even more energy than liquids, their particles are moving around a lot more, too. This is why a gas will expand to fill its entire container, not just to its surface like a liquid. Not only do the particles of a solid not move very much, but they're also held very close to each other by strong attractive forces. These forces are what hold the particles in place and are what give a solid its fixed size and shape.
On the other hand, the particles of a gas are so far apart that the attractive forces between them are assumed to be negligible. The particles of a gas are viewed as independent from each other, meaning that the gas is the opposite of a solid and has neither a fixed size nor shape.
Since the movement of liquid particles is in between a solid and a gas, the attractive forces between its particles are also in a middle range of the other two phases. Liquid particles have more freedom than solid particles, which is why a liquid can flow freely. This means that like a gas, a liquid has no fixed shape. But because the particles aren't quite as free as those of a gas, a liquid does have a fixed volume.

thanks for asking

Question

Ball A has mass 5.0 kg and is moving at -3.2 m/s when it strikes stationary ball B, which has mass 3.9 kg, in a head-on collision. If the collision is completely inelastic, what is the common velocity of balls A and B?

Solution 1

Momentum conservation in a completely inelastic collision works like this:
mA*vA+mB*vB=v(mA+mB)

Since B was initially stationary pB=0.
Plugging in numbers gives:
5*(-3.2)=v(5+3.9)
v= -1.79 m/s to the left.

Solution 2

Answer:

A.) -0.40 m/s

B.) -3.60 m/s

C.) -1.80 m/s

Explanation:

By the law of momentum conservation:-

=>m1u1 + m2u2 = m1v1 + m2v2

=>5 x (-3.2) + 0 = 5v1 + 3.9v2

=>1.28v1 + v2 = -4.10 ---------------(i)

for elastic collision:-

=>v1 - v2 = u2 - u1

=>v1 - v2 = 0 - (-3.2)

=>v1 - v2 = 3.2 ------------------(ii)

by (i) + (ii) :-

=>2.28v1 = -0.90

=>v1 = -0.40 m/s

=>v2 = -3.60 m/s

=>m1u1+m2u2 = (m1+m2)v

=>5 x (-3.2) + 0 = (5 + 3.9) x v

=>v = -1.80 m/s

Question

The root word terra means “land” or “territory.” Terrestrial planets are the planets closest to the Sun. Why are they are called terrestrial planets?

Solution 1

A Terrestrial plant, Tell-uric planet, or rock planet is a planet that is composed primarily of silicate rocks or metals.

Solution 2

Answer:

They are made of rock and metal.

Explanation:

The planets closest to the Sun are called terrestrial planets because they are made of rock and metal. Plato

Question

How did scientists discover the Earth had a liquid outer core and solid inner core?

Solution 1

Dr. Inge discovered the make up of the earths inner core by studying how an earthquakes waves bounced off the core. And Inge Lehmann was studying the waves of a 1929 earthquake when she found them acting inconsistently with solid mantle crust
hope it helps you

Question

Which of these statements best describes the relationship between matter, pure substances, and mixtures?

Solution 1

The answer is matter

Question

A car initially at rest undergoes uniform acceleration for 6.32 seconds and covers a distance of 120 meters. What is the approximate acceleration of the car?

Solution 1

Answer : The approximate acceleration of the car is, $6.008m/s^2$

Solution : Given,

Initial velocity of the car = 0 m/s

Distance covered = 120 meter

Time taken = 6.32 second

Using second law of motion,

$s=ut+\frac{1}{2}at^2$

where,

s = distance covered

u = initial velocity

t = time taken

a = acceleration

Now put all the given values in the above equation, we get

$(120m)=(0m/s)\times (6.32s)+\frac{1}{2}\times a\times (6.32s)^2$

$a=6.008m/s^2$

Therefore, the approximate acceleration of the car is, $6.008m/s^2$

Solution 2

Using kinematic equation s=ut + 1/2 at^2(u = initial velocity=0, s=120m, t= 6.32s), 120 = 0(t) + 1/2 a(6.32)^2. a = 120x2/(6.32)^2 = 6m/s^2.

Question

When Nina jumps into the air, the Earth pulls her back down through the force of gravity. What else occurs? Nina’s gravitational force pushes away from the Earth. Nina exerts a gravitational pull on the Earth, but the Earth does not accelerate at all. Nina pulls the Earth toward her, but the Earth’s acceleration is too small to notice. The force of gravity pulling Nina back down to Earth is the only force occurring.

Solution 1

It is A. hope this helps

Solution 2

1) WRONG. Since gravitational force is an attractive force.
2) WRONG. The Earth does accelerate but the acceleration is so small that it's negligible. However it DOES ACCELERATE.
3) CORRECT.
4) WRONG. Mass means gravitational field, so Nina might be small compared to the Earth but it still creates a gravitational field around her. This answer is also wrong because it's breaking Newton's third law of action-reaction. If Earth pulls Nina, then Nina pulls the Earth back with the same force. Yes, with the SAME FORCE, however F=m*a, so the great difference in mass makes Nina's acceleration much bigger than the Earth's one.

Question

The speed of an object determines the amount of inertia? True or False

Solution 1

The answer to this question is false.

Solution 2

The answer to your question is false.

Question

A plane is traveling with an air velocity of 720 kilometers/hour due east. It experiences a headwind of 16 kilometers/hour. Find the resultant velocity and direction of the plane with respect to the ground.

Solution 1

Answer:

The resultant velocity and direction of the plane with respect to the ground is 704 km/h due east.

Explanation:

Given that,

Air velocity v₁= 720 km/h

Headwind v₂ = 16 km/h

The air velocity due to east is greater then the head wind.

So, the direction of the velocity respect to the ground will be due to east.

The velocity of plane respect to ground

The resultant velocity will be

$v= v_{1}-v_{2}$

$v = 720-16$

$v = 704\ km/h$

Hence, The resultant velocity and direction of the plane with respect to the ground is 704 km/h due east.

Solution 2

If it is a headwind it means it's travelling against the motion of the plane. This means it's velocity is simply v=720-16=704 km/h due east.

Question

Select all the correct answers. In which situations is work being done? A. Hannah leans against her locker, but it doesn’t move. B. Andy’s car rolls down a hill with the engine off. C. A wind turbine stands still on a sunny, windless day. D. A balloon expands as it is heated by the Sun. E. James pedals a stationary exercise cycle that doesn’t move.

Solution 1

E. James pedals a stationary exercise cycle that doesn’t move.

B. Andy’s car rolls down a hill with the engine off.
These Answer's Are Correct For It Show's Work Being Done A Car Moving Is Working, Pedaling A Exercise Machine Is Working Even If It Doesn't Move It Is Meant To Help You Work Out Pedaling Help's There Is No Need For It To Move.

Solution 2

Answer: The statements B and D are correct answers.

Explanation:

Work is done when the force is applied to an object then there will be displacement by the object.

In the option A, Hannah leans against her locker, but it doesn’t move. There is no displacement in this case. The work done is said to be zero in this case.

In the option B, Andy’s car rolls down a hill with the engine off. There is displacement in this case. The work is said to done in this case. At the hill, the car has a maximum potential energy.

When it rolls down then the kinetic energy of the car will increase. From the work energy theorem, the change in the kinetic energy is equal to the work done.

In the option C, A wind turbine stands still on a sunny, windless day. The work done is said to zero in this case.

In the option, A balloon expands as it is heated by the Sun. There is expansion of the balloon. The work is done in this case as the volume and the pressure will also increase on heating the balloon.

In the option E, James pedals a stationary exercise cycle that doesn’t move. No work is done in this case.

Therefore, the statements B and D are correct answers.

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