Answer:
<em>The initial speed of the sprinter was 2.2 m/s</em>
Explanation:
<u>Constant Acceleration Motion</u>
It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.
The following relation applies:

Where a is the constant acceleration, vo the initial speed, vf the final speed, and t the time.
The sprinter speeds up from an unknown initial speed to vf=3 m/s in t=2 seconds with an acceleration of
.
To find the initial speed, we solve the equation for vo:

Substituting the values:



The initial speed of the sprinter was 2.2 m/s
Answer:
7800 J
Explanation:
Heat needed = mass of copper x specific heat of copper x change in temperature
Change in temperature = 30ºC - 20ºC = 10ºC
Specific heat of copper = 390 J/kgºC
Mass of copper = 2 Kg
Substituting the given values in above equation, we get –
Heat needed = 2 Kg x 390 J/kgºC x 10ºC
= 7800 J
Of the gravitational pull and other things like mass. Planet earth it,s self as you said sir.
On the list of choices that you provided, there is no such statement.
The value of the underlined 8 is, hundred billion's. Hope this helped!