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2 years ago

Which is true?

Physics

2 answers:

nikklg [1K]2 years ago

7 0

The correct answer is C. Light waves slow down as they travel from the air though the water.

aniked [119]2 years ago

6 0

Light waves slow down when they go from air into water. Then, once they're in the water and traveling through it, they don't change speed.

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Sam is riding his bike in the park when he sees a soccer ball rolling toward him. He applies his brakes to slow down. Once he st

nlexa [21]

When Sam presses the brake lever, a pair of rubber shoes clamps onto the metal inner rim of the front and back wheels. As the brake shoes rub against the wheels, friction is caused and the kinetic energy possessed by the vehicle is converted into heat which slows down the vehicle.

3 0

2 years ago

Give two reasons why hydroelectricity could be better alternative of biofuel in the context of our country.

Semmy [17]

Answer:

Hydroelectricity is a renewable energy source.

Hydroelectricity increases the stability and reliability of electricity system

Hydroelectricity helps fight climate changes.

Explanation:

If we use hydroelectricity our country would be in good climate and not a bad one. And the best facts it is renewable.

3 0

2 years ago

You stand on a frictionless platform that is rotating with an angular speed of 5.1 rev/s. Your arms are outstretched, and you ho

timurjin [86]

Answer:

$\omega'=19.419\ rev.s^{-1}$

Explanation:

Given:

angular speed of rotation of friction-less platform, $\omega=5.1\ rev.s^{-1}$

moment of inertia with extended weight, $I=9.9\ kg.m^2$

moment of inertia with contracted weight, $I'=2.6\ kg.m^2$

Now we use the law of conservation of angular momentum:

$I.\omega=I'.\omega'$

$9.9\times 5.1=2.6\times \omega'$

$\omega'=19.419\ rev.s^{-1}$

The angular speed becomes faster as the mass is contracted radially near to the axis of rotation.

5 0

3 years ago

The record distance in the sport of throwing cowpats is 81.1 m. This record toss was set by Steve Urner of the United States in

N76 [4]

Answer:

28.2 m/s

Explanation:

The range of a projectile launched from the ground is given by:

$d=\frac{v^2}{g}sin 2\theta$

where

v is the initial speed

g = 9.8 m/s^2 is the acceleration of gravity

$\theta$ is the angle at which the projectile is thrown

In this problem we have

d = 81.1 m is the range

$\theta=45^{\circ}$ is the angle

Solving for v, we find the speed of the projectile:

$v=\sqrt{\frac{dg}{sin 2 \theta}}=\sqrt{\frac{(81.1 m)(9.8 m/s^2)}{sin (2\cdot 45^{\circ})}}=28.2 m/s$

7 0

2 years ago

12 seconds after starting from rest a frewly falling cantaloupe has a speed of

adoni [48]

Answer:

The cantaloupe has a speed of 117.6 m/s

Explanation:

Free Fall Motion

It occurs when an object falls under the sole influence of gravity. Any object that is being acted upon solely by the force of gravity is said to be in a state of free fall. Free-falling objects do not face air resistance.

If an object is dropped from rest in a free-falling motion, it falls with a constant acceleration called the acceleration of gravity, which value is $g = 9.8 m/s^2$ .

The final velocity of a free-falling object after a time t is given by:

vf=g.t

The cantaloupe has been dropped from rest. We are required to find the speed after t=12 seconds.

Calculate the final speed:

vf=9.8 * 12 = 117.6 m/s

The cantaloupe has a speed of 117.6 m/s

3 0

2 years ago