PHYSICS HIGH SCHOOL

Suppose a yo-yo has a center shaft that has a 0.230 cm radius and that its string is being pulled.(a) If the string is stationary and the yo-yo accelerates away from it at a rate of 1.80 m/s2, what is the angular acceleration of the yo-yo in rad/s2? rad/s2.
(b) What is the angular velocity in rad/s after 0.750 s if it starts from rest? rad/s.
(c) The outside radius of the yo-yo is 3.10 cm.What is the tangential acceleration in m/s2 of a point on its edge? m/s2

Answers

Answer 1

Answer:

Answer:

Part a)

$\alpha = 782.6 rad/s^2$

Part B)

$\omega = 587 rad/s$

Part c)

$a_t = 24.3 m/s^2$

Explanation:

Part a)

As we know that

$a = R \alpha$

so we will have

$a = 1.80 m/s^2$

$R = 0.230 cm$

$\alpha = (a)/(R)$

$\alpha = (1.80)/(0.230 * 10^(-2))$

$\alpha = 782.6 rad/s^2$

Part B)

Angular speed of the yo-yo

$\omega = \alpha t$

so we have

$\omega = 782.6 * 0.750$

$\omega = 587 rad/s$

Part c)

Tangential acceleration is given as

$a_t = R \alpha$

$a_t = (3.10 * 10^(-2))(782.6)$

$a_t = 24.3 m/s^2$

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Which of the following could classify as a non-essential need according to the hierarchy of needs? A. healthy food B. human contact C. more sleep D. new clothes

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D. According to the hierarchy of needs the body and mind must be taken care of first and foremost.

Answer:

D. New Clothes

A 4kg block sitting on the floor, how much potential energy does it have?

Answers

Well, there you have a very important principle wrapped up in that question.

There's actually no such thing as a real, actual amount of potential energy.
There's only potential relative to some place. It's the work you have to do
to lift the object from that reference place to wherever it is now. It's also
the kinetic energy the object would have if it fell down to the reference place
from where it is now.

Here's the formula for potential energy: PE = (mass) x (gravity) x (height) .

So naturally, when you use that formula, you need to decide "height above what ?"

If you're reading a book while you're flying in a passenger jet, the book's PE is
(M x G x 0 meters) relative to your lap, (M x G x 1 meter) relative to the floor of the
plane, (M x G x 10,000 meters) relative to the ground, and maybe (M x G x 25,000 meters)
relative to the bottom of the ocean.

Let's say that gravity is 9.8 m/s² .

Then a 4kg block sitting on the floor has (39.2 x 0 meters) PE relative to the floor
it's sitting on, also (39.2 x 3 meters) relative to the floor that's one floor downstairs,
also (39.2 x 30 meters) relative to 10 floors downstairs, and if it's on the top floor of
the Amoco/Aon Center in Chicago, maybe (39.2 x 345 meters) relative to the floor
in the coffee shop that's off the lobby on the ground floor.

P.E.=mgh

P.E.= mass×gravity×height, therefore 4kg×10×0= 0 J

K.E. is also equal to 0 because the block is not moving, is in the state of Inertia

BY what factor does the kinetic energy of a moving body change when its speed is reduced to half? please help i have an exam and i need an answer

Answers

Answer:

Kinetic Energy = 1/2 mass*velocity^2

K=1/2mv^2

Therefore if you reduce the speed of an object by 1/2, K reduced to 1/4 its value.

What experimental evidence was provided for the nuclear model of the atom?

Answers

The correct answer is:

Alpha particles bouncing off gold foil

Explanation:

The nuclear model. Atoms contain three sub-atomic particles termed protons, neutrons, and electrons. The protons and neutrons are determined in the nucleus at the center of the atom. The nucleus is surprisingly much less than the atom as a whole. The Rutherford Gold Foil Experiment conceded the first empirical confirmation that guided to the development of the nucleus of the atom as a small, dense, and positively charged atomic core.

The nuclear model of atom was given by Rutherford. As per this model,the central part of every atom is a massive positive core, and it occupies the total mass of the atom .Around the nucleus, there are orbits in which electrons are revolving just like planets are revolving around the sun.

This evidence was provided by Rutherford's gold foil experiment.

As per this experiment, some alpha particles were deviated at an angle less than 90 degree when allowed to fall on a gold foil.Some alpha particles were deviated more than 90 degree.

One alpha particle out of 10000 particles directly retraced its path back i.e it was deviated at angle of 180 degree.

It is so because alpha particle is positively charged. The alpha particle will be deviated if it will suffer a repulsive force. Hence, the central part of atom is positively charged. As alpha particle comes back, it means the central part is very massive.

Why does a moving object come to a stop on a frictional surface? a.The object’s kinetic energy is transformed into mainly heat energy. b.The object’s potential energy is transformed into mainly kinetic energy. c.The object loses all its energy in deformation. d.The object’s kinetic energy is transformed into mainly potential energy.

Answers

The correct answer to the question is - A) Object's kinetic energy is transformed into mainly heat energy.

EXPLANATION:

The friction is the opposing force which acts tangentially between two surfaces when there is a relative velocity between them.

As per the question, the moving object comes to rest after the application of frictional force.

Initially the object is in motion.Hence, the energy possessed by the moving object is kinetic energy.

When frictional force is applied on the moving object, the kinetic energy of the moving object will be converted into mainly heat energy. It is due to the fact that friction causes heat production between two surfaces in contact.

Hence, correct option will be that the object's kinetic energy is transformed into mainly heat energy.

A) the objects kinetic energy is transformed into mainly heat energy

That "heat energy" is called fricton

What is the acceleration of a 5.9 kilogram bowling ball if a force of 11 N is applied to it?