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3 years ago

3. The direction of the centripetal force acting on a ball on a string being spun in a circle around a person is

Physics

2 answers:

Yakvenalex [24]3 years ago

6 0

Answer: The correct answer is "center-seeking".

Explanation:

Centripetal force is the force which is required to keep the body in the circular motion. The direction of the centripetal force is towards center of the circle.

The expression for the centripetal force is as follows;

$F= \frac{mv^{2} }{r}$

Here, r is the radius, v is the velocity and m is the mass of the object.

Without this force, the body cannot move in the circular motion. Then, it follows the straight line motion.

The direction of the centripetal force acting on a ball on a string being spun in a circle around a person is center-seeking.

Therefore, the correct option is (D).

ruslelena [56]3 years ago

4 0

D. center seeking. Good Luck

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The cylinder with piston locked in place is immersed in a mixture of ice and water and allowed to come to thermal equilibrium wi

lukranit [14]

Answer:

a. volume of gas: (decreases)

b. temperature of gas: (same)

c. internal energy of gas: (same)

d. pressure of gas: (increases)

Explanation:

We have a gas (let's suppose that is ideal) in a piston with a fixed volume V.

Then we put in a reservoir at 0°C (the mixture of water and ice)

remember that the state equation for an ideal gas is:

P*V = n*R*T

and:

U = c*n*R*T

where:

P = pressure

V = volume

n = number of mols

R = constant

c = constant

T = temperature.

Now, we have equilibrium at T = 0°C, then we can assume that T is also a constant.

Then in the equation:

P*V = n*R*T

all the terms in the left side are constants.

P*V = constant

And knowing that:

U = c*n*R*T

then:

n*R*T = U/c

We can replace it in the other equation to get:

P*V = U/c = constant.

Now, the piston is (slowly) moving inwards, then:

a) Volume of the gas: as the piston moves inwards, the volume where the gas can be is smaller, then the volume of the gas decreases.

b) temperature of the gas: we know that the gas is a thermal equilibrium with the mixture (this happens because we are in a slow process) then the temperature of the gas does not change.

c) Internal energy of the gas:

we have:

P*V = n*R*T = constant

and:

P*V = U/c = constant.

Then:

U = c*Constant

This means that the internal energy does not change.

d) Pressure of the gas:

Here we can use the relation:

P*V = constant

then:

P = (constant)/V

Now, if V decreases, the denominator in that equation will be smaller. We know that if we decrease the value of the denominator, the value of the quotient increases.

And the quotient is equal to P.

Then if the volume decreases, we will see that the pressure increases.

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2 years ago

A uniform solid disk rolls without slipping down an incline making an angle θ with the horizontal. What is its acceleration? (En

Maru [420]

Answer:

aCM = (2/3)*g*Sin θ

Explanation:

Consider a uniform solid disk having mass M, radius R and rotational inertia I about its center of mass, rolling without slipping down an inclined plane.

In order to get the linear acceleration of the object’s center of mass, aCM ,

down the incline, we analyze this as follows:

The force of gravity (W = Mg) acting straight down is resolved into components parallel and perpendicular to the incline.

Since the object rolls without slipping there is a force of friction (Ff) acting on the object, at it’s point of contact with the incline, in the direction up the incline.

Newton’s 2nd Law gives then for acceleration down the incline

∑Fx' = m*aCM ⇒ m*g*Sin θ - Ff = m*aCM

The force of friction also causes a torque around the center of mass

having lever arm R so we can also write

τ = R*Ff = I*α

Solving for the friction, Ff = I*α / R

This is used in the expression derived from the 2nd Law:

m*g*Sin θ - Ff = m*g*Sin θ - (I*α / R) = m*aCM

The objects angular acceleration is related to the linear acceleration of the edge that contacts the incline by

a = R*α

Since the object rolls without slipping this has the same magnitude as aCM so we have that

α = aCM / R

Using this in

m*g*Sin θ - (I*α / R) = m*g*Sin θ - (I*(aCM / R) / R) = m*aCM

⇒ aCM = (m*g*Sin θ*R²) / (I + m*R²)

if I = (1/2)*m*R² (for a uniform solid disk)

we get

aCM = (2/3)*g*Sin θ

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3 years ago

A 1200-kg car accelerates it’s speed from 4 m/s to 10 m/s in 3 seconds. Find the car average speed , the car acceleration , the

dsp73

Answer:

Given: mass 1200kg

initial velocity: 4m/s

finial velocity: 10 m/s

time 3 sec

then

speed; initial velocity + final velocity/2

4+10/3

: 4.66m/s2

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3 years ago

Why does the total amount of energy before and after any energy transformations remain the same?

Georgia [21]

The amount of energy before and after any energy transformations remain the same because energy cannot be created or destroyed. From the law conservation of energy; any time energy is transferred between two objects, or converted from one form into another, no energy is created and none is destroyed. The total amount of energy involved in the process remains the same.

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3 years ago

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You endanger a swimmer with the wake from your boat. under minnesota boating laws, what have you done?

mixas84 [53]

The following enumeration is the list of actions which are considered to be illegal when operating your boat:

1 Operating the boat in a harsh or inconsiderate manner

2 Operating the boat in the absence of safety equipment

3 Actual weight exceeds the carrying capacity of the boat

4 Not prohibiting the riders to sit on gunwales, transom, stern, sides, bow or decking over the bow sides when the boat is underway, except when sufficient guards or railings are provided

5 Operating the boat or giving permission to other people to operate the boat while drunk or under illegal substances

6 Operating the boat and the wash or wake endanger any property or person

7 Operating the boat in an area designated for swimming

8 Operating the boat beyond a slow, no wake speed in locations marked as no wake zones

We can see that in this case, the rule # 6 is being trespassed. Therefore under Minnesota Boating Laws, we have committed an Illegal Operating Practice.

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3 years ago