The speed of sound in a solid would be 6000 metres per second
Answer:
The positive velocity occurs the instant the coin leaves our hand. It immediately begins slowing up until its upward velocity becomes zero at the maximum height.
Explanation:
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Answer:
A force of 12.857 newtons must be applied to open the door.
Explanation:
In this case, a force is exerted on the door, a moment is performed and the door is opened. If moment remains constant, the force is inversely proportional to distance respect to axis of rotation passing through hinges. That is:

(Eq. 1)
Where:
- Force, measured in newtons.
- Proportionality ratio, measured in newton-meters.
- Distance respect to axis of rotation passing through hinges, measured in meters.
From (Eq. 1) we get the following relationship and clear the final force within:
(Eq. 2)
Where:
,
- Initial and final forces, measured in newtons.
,
- Initial and final distances, measured in meters.
If we know that
,
and
, then final force is:


A force of 12.857 newtons must be applied to open the door.
The four equations for acceleration are obtained from the three equations of motion and from second law of motion.
Explanation:
Acceleration is defined as the rate of change of velocity with respect to time. So the change in velocity with respect to time can be determined using the three equations of motions.
So from the first equation of motion, v = u + at , we can determine the value of acceleration if time taken, final and initial velocity is known. The equation can be re-written as 
Similarly, from the second equation of motion, s = ut + 1/2 at², we can determine the equation for acceleration as 
So this is second equation for acceleration.
Then from the third equation of motion, 
the acceleration equation is determined as 
In addition to these three equation, another equation is present to determine the acceleration with respect to force from the Newton's second law of motion. F = Mass × acceleration. From this, acceleration = Force/mass.
So, these are the four equations for acceleration.