<em>number of waves that pass a given point in one second is called <u>frequency..</u></em>
The middle or centre of the Earth is the core. However the middle of the layers from the surface to the centre of the Earth is known as mantle.
For a body moving at a uniform velocity you can calculate the speed by dividing the distance traveled by the amount of time it took, for example one mile in 1/2 hour would give you 2 miles per hour. If the velocity is non-uniform all you can say is what the average speed is.
HOPE IT HELPS YOU
When a car travelling at an initial velocity of 10 m/s applies the brakes and bring ... accelerates from rest for a time of 8 seconds with an acceleration of 3.2m/s^2?
One, three and five are correct.
Although if the second statement is saying that stars use gravitational force to support nuclear fusion which in turn produces energy then that would be correct, but I don’t think so :)
