Speed of light
According to Einstein, the speed of light is constant in all points of reference. In addition, he pointed out the speed of light is the maximum speed known since in practice one can never catch up with the beam of light. This is explained by his theory of relativity.
Answer:
Bent knees
Explanation:
Depending the height your jumping from, if you were jumping from a high structure it's best if you jump and land on knees so you dont sprang your ankles from jumping and landing on your straight legs, you could even pull a muscle if you land on straight legs.
Answer:

Explanation:
A force exerts work when there is a displacement of its point of application in the direction of that force. Therefore, the work done by a system is defined as the inner product between the applied force and the displacement:

In this case, we have:

So, replacing this:

As per the question, the distance travelled by bobsled [s] = 100 m
The time taken by the bobsled to travel that distance [t] = 25 s
We are asked to calculate the speed of the bobsled.
The speed of the bobsled is calculated as -




Hence, the correct answer to the question is A. 4 m/s.
Solution :
We know that :
Formula for Gravitational force is given by :

where, G is the gravitational constant
M is the mass of the bigger body
m is the mass of the smaller body
r is the distance between the two bodies.
And the formula for the centripetal force is given by :

where, m is the mass of the rotating body
v is the velocity
r is the radius of rotation of the body.
We know that mathematically, the gravitational force is equal to the centripetal force of the body.
Therefore,



Hence derived.