Explanation:
velocity is distance divided by time.
so
the average speed of the ball is 10m/20s
= 0.5 m/s
1. Heat raises the temperature.
2. It increases volume.
3. It changes state.
4. Brings about chemical action.
5. Changes physical properties.
<h3>Hope this helps :)</h3>
Explanation:
We need to apply the conservation law of linear momentum to two dimensions:
Let
= momentum of the 1st ball
= momentum of the 2nd ball
In the x-axis, the conservation law can be written as

or

Since we are dealing with identical balls, all the m terms cancel out so we are left with

Putting in the numbers, we get


In the y-axis, there is no initial y-component of the momentum before the collision so we can write

or

Taking the ratio of the sine equation to the cosine equation, we get

or

Solving now for
,

2.3 seconds
Ignoring air resistance, the flight time is merely a function of gravity and vertical velocity. The vertical velocity will be the initial velocity multiplied by the sine of the angle above the horizon. So:
V = sin(72)*12 m/s
V = 0.951056516 * 12 m/s
V = 11.4126782 m/s
Gravitational acceleration is 9.8 m/s, so divide the vertical velocity by gravitational acceleration to get how long it takes for the ball to reach its apex.
11.4126782 m/s / 9.8 m/s^2 = 1.164559 s
And the old saying "What goes up, must come down" really applies here. And conveniently, it's also symmetric, in that the time it takes to fall will match the time it takes to reach its apex. So multiply the time by 2.
1.164559 s * 2 = 2.329117999 s
Rounding the result to 2 significant figures gives 2.3 seconds.