Kinetic energy is never negative, but potential energy can be.
Potential energy depends on height above some reference level,
and you can pick any level you want as the reference. So, if the
object is below the reference level you pick, then its potential
energy relative to your reference level is negative.
What that means is: You have to lift it / do work on it / give it more
energy than it has now ... in order to move it to the reference level.
(That's exactly the situation with electrons bound to an atom. Their
energy is considered negative, because we have to do work and
give them more energy to rip them away from the atom.)
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Regarding the other choices:
-- Kinetic energy is scalar ... Yes. So is potential energy.
-- Kinetic energy increases with height ...
No. It doesn't, but potential energy does.
-- Kinetic energy depends on position ...
No. It doesn't, but potential energy does.
Answer:
I=2 kg.m/s
Explanation:
The impulse is defined as the change of momentum:
![I=p_f-p_o\\I=m*v_f-m*v_o\\I=0.02kg*[(-60m/s)-40m/s]\\I=2kg.m/s](https://tex.z-dn.net/?f=I%3Dp_f-p_o%5C%5CI%3Dm%2Av_f-m%2Av_o%5C%5CI%3D0.02kg%2A%5B%28-60m%2Fs%29-40m%2Fs%5D%5C%5CI%3D2kg.m%2Fs)
We took the final velocity as negative since it is going on the opposite direction of the intial motion of the ball.
Answer:
ω = 1.83 rad/s clockwise
Explanation:
We are given:
I1 = 3.0kg.m2
ω1 = -5.4rad/s (clockwise being negative)
I2 = 1.3kg.m2
ω2 = 6.4rad/s (counterclockwise being positive)
By conservation of the momentum:
I1 * ω1 + I2 * ω2 = (I1 + I2) * ω
Solving for ω:
Since it is negative, the direction is clockwise.
Because it's so much closer to us than any other star.
The concave mirror is a spherical-shaped mirror that has an inner curved surface. Hence, option (4) is correct.
What is a concave mirror?
The concave mirrors are spherical-shaped mirrors that are painted on the outward surface. It is also known as the converging mirror, having the recessed inner reflecting surface.
- The concave mirrors are generally used for the purpose to focus the light. For that, they might have a reflecting surface, curved inwards, and the reflection of light is limited to the single focal point.
- The reflecting surface of the concave mirror has its vertex or midpoint lying farther away from the objects than the edges.
Thus, we can conclude that the surface of the concave mirror is curved inward. Hence, option (4) is correct.
Learn more about the concave mirror here:
brainly.com/question/13300307
