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3 years ago

Which of the following will be hardest to stop?

2 answers:

7 0

C, elephant since is hard to stop something heavy. Speed can make something hard to stop but weight*speed makes something harder to stop

Dvinal [7]3 years ago

3 0

Answer:OD. a hummingbird moving at 25 mph

Explanation:

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A compact disc (CD) stores music in a coded pattern of tiny pits 10⁻⁷m deep. The pits are arranged in a track that spirals outwa

Serggg [28]

a) Angular speed of the innermost part: 50 rad/s, outermost part: 21.6 rad/s

b) The length of the track would be 5,550 m

c) The average angular acceleration is $-6.4\cdot 10^{-3}rad/s$

Explanation:

For an object in uniform circular motion, the relationship between angular speed and linear speed is

$v=\omega r$

where

v is the linear speed

$\omega$ is the angular speed

r is the radius of the circle

Here the linear speed of the track is constant:

v = 1.25 m/s

For the innermost part of the disk,

r = 25.0 mm = 0.025 m

So the angular speed is

$\omega_i = \frac{v}{r_i}=\frac{1.25}{0.025}=50 rad/s$

For the outermost part,

r = 58.0 mm = 0.058 m

So the angular speed is

$\omega_o = \frac{v}{r_o}=\frac{1.25}{0.058}=21.6 rad/s$

The maximum playing time of the disk is

$t=74.0 min \cdot (60 s/min)=4440 s$

If the track was stretched out in a straight line, the motion of the track would be a uniform motion (since it is moving at constant speed), so we can use the equation

$v=dt$

where

v is the linear speed

d is the length coverted in a straight line

t is the time

Substituting v = 1.25 m/s and solving for d,

$d=vt=(1.25)(4440)=5550 m$

The angular acceleration is given by

$\alpha = \frac{\omega_f - \omega_i}{t}$

where

$\omega_f$ is the final angular speed

$\omega_i$ is the initial angular speed

t is the time

A CD is read from the innermost part to the outermost part, so we have:

$\omega_i = 50 rad/s$ (at the innermost part)

$\omega_f = 21.6 rad/s$ (at the outermost part)

t = 74.0 min = 4440 s is the time

Substituting, the average angular acceleration is

$\alpha = \frac{21.6-50.0}{4440}=-6.4\cdot 10^{-3}rad/s$

where the negative sign means the CD is decelerating.

Learn more about circular motion:

brainly.com/question/2562955

brainly.com/question/6372960

#LearnwithBrainly

6 0

2 years ago

A car’s velocity changes from 35 m/s to stopped in 13 seconds. Calculate acceleration.

padilas [110]

Answer:

Acceleration = 3m/s^2

Vf= 0 Vi =35m/s t= 13s

Explanation:

$Acceleration = \frac{Change in velocity}{Change in time}\\ = \frac{35m/s}{13s}\\ a = 2.69m/s^2\\ a = 2.7m/s^2\\ a = 3m/s^2$

5 0

2 years ago

1. Which one of the following physical quantities is formed after dividing mass by volume?

aivan3 [116]

Answer:

xxxxx

Explanation:

Density is the mass of an object divided by its volume. Density often has units of grams per cubic centimeter (g/cm3). Remember, grams is a mass and cubic centimeters is a Volume (the same volume as 1 milliliter).

3 0

2 years ago

Physics/Math

Korolek [52]

Answer:

f = pl / (l + p)

Explanation:

1/f = 1/p + 1/l

Find the common denominator of the right hand side.

1/f = l/(pl) + p/(pl)

Add:

1/f = (l + p) / (pl)

Take the inverse of both sides:

f = pl / (l + p)

6 0

3 years ago

According to Newton’s law of universal gravitation, which statements are true?

andreyandreev [35.5K]

Before we solve this, we should know this fact:

According to Newton's Law of Gravitation, the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The force acts along the line joining the centres of the two objects. It can be shown by this:

$F ∝ \frac{Mm}{ {d}^{2} }$

Now, let us check all the options.

A. As we move to higher altitudes, the force of gravity on us decreases.

This statement is true.

The force of gravity is inversely proportional to the square of distance from the centre of the earth. If, we go up the surface of the earth, the distance from the centre of the earth increases and hence the value of force of gravity decrease. So, force of gravity decreases with altitude.

B. As we move to higher altitudes, the force of gravity on us increases.

This statement is false.

We have already got the result in option A. that the force of gravity decreases with altitude. It never increases with altitude.

C. As we gain mass, the force of gravity on us decreases.

This statement is false.

The force of gravity is directly proportional to the product of the masses. So, if increase our mass, then the force of gravity will also increase and if we decrease our mass, then the force of gravity decreases.

D. As we gain mass, the force of gravity on us increases.

This statement is true.

As mentioned earlier in option C., the force of gravity is directly proportional to the product of the masses of the earth and another object. So, as we gain mass, the force of gravity on us increases.

E. As we move faster, the force of gravity on us increases.

This statement is true.

Here, we have to consider a different formula. According to Newton's Second Law,

F = ma, where F is the force, m is the mass and a is the acceleration.

In other words,

F ∝ a, i.e., force is directly proportional to acceleration.

We know, acceleration is the rate of change of velocity of an body within a time period.

So, if speed is increased, then acceleration will also be greater, which results in the increase of force. So, as we move faster, the force of gravity on us increases.

Answers:

A: As we move to higher altitudes, the force of gravity on us decreases.

D: As we gain mass, the force of gravity on us increases.

E: As we move faster, the force of gravity on us increases.

Hope you could understand.

If you have any query, feel free to ask.

7 0

1 year ago