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3 years ago

Which system protects us from radiation and the vacuum of space

2 answers:

6 0

It is the Earth's atmosphere that protects us from radiation and the vacuum of space--specifically UV radiation from the Sun, which can be very dangerous even with the atmosphere's intervention.

mars1129 [50]3 years ago

4 0

Ozone Layer, Atmosphere.

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When water change into ice it contracts or expand plz answer fast..

mihalych1998 [28]

Answer:Yes, water indeed expands when it changes form from liquid to solid. And this is because water has a property called “hydrogen bonds”, and these bonds occur between each water molecule. But when water is in a liquid form these hydrogen bonds break more easily and occur less frequently. When the temperature drops the kinetic energy also drops, which in turn makes hydrogen bonds form more frequently. So the water molecules form a lattice, which is less dense than regular liquid water.

Explanation:

4 0

3 years ago

Read 2 more answers

The velocity of a car is 65 m/s and it’s mass is 2515 kg. What is it’s KE?

Aloiza [94]

Example Problems. Kinetic Energy (KE = ½ m v2). 1) The velocity of a car is 65 m/s and its mass is 2515 kg. What is its KE? 2) If a 30 kg child were running at a rate of 9.9 m/s, what is his KE? Practice Problems. IN THIS ORDER…. Page 2: #s 6, 7, 8, 5. Potential Energy. An object can store energy as the result of its position.

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3 years ago

Read 2 more answers

A girl (mass M) standing on the edge of a frictionless merry-go-round (radius R, rotational inertia I) that is not moving. She t

vladimir1956 [14]

a) $\omega=\frac{-mvR}{I+MR^2}$

b) $v=\frac{-mvR^2}{I+MR^2}$

Explanation:

Since there are no external torques acting on the system, the total angular momentum must remain constant.

At the beginning, the merry-go-round and the girl are at rest, so the initial angular momentum is zero:

$L_1=0$

Later, after the girl throws the rock, the angular momentum will be:

$L_2=(I_M+I_g)\omega +L_r$

where:

$I$ is the moment of inertia of the merry-go-round

$I_g=MR^2$ is the moment of inertia of the girl, where

M is the mass of the girl

R is the distance of the girl from the axis of rotation

$\omega$ is the angular speed of the merry-go-round and the girl

$L_r=mvR$ is the angular momentum of the rock, where

m is the mass of the rock

v is its velocity

Since the total angular momentum is conserved,

$L_1=L_2$

So we find:

$0=(I+I_g)\omega +mvR\\\omega=\frac{-mvR}{I+MR^2}$

And the negative sign indicates that the disk rotates in the direction opposite to the motion of the rock.

The linear speed of a body in rotational motion is given by

$v=\omega r$

where

$\omega$ is the angular speed

r is the distance of the body from the axis of rotation

In this problem, for the girl, we have:

$\omega=\frac{-mvR}{I+MR^2}$ is the angular speed

$r=R$ is the distance of the girl from the axis of rotation

Therefore, her linear speed is:

$v=\omega R=\frac{-mvR^2}{I+MR^2}$

5 0

3 years ago

Swinging a golf club or baseball bat are examples of ______________ stretching.

kari74 [83]

Answer:

Static stretching is the answer.

Explanation:

Static stretching is the most common form that greatly improves flexibility. However, static stretches does little to contract the muscles needed to generate powerful golf swings. Dynamic stretches help improve your range of motion while reducing muscle stiffness.

6 0

4 years ago

Suppose a ball is dropped from shoulder height, falls, makes a perfectly elastic collision with the floor, and rebounds to shoul

Bezzdna [24]

Answer:Same magnitude

Explanation:

When ball is dropped from shoulder height h then velocity at the bottom is given by

$v_1=\sqrt{2gh}$