Answer:
The kinetic energy is 20,000\ J
Step-by-step explanation:
The kinetic energy of a body is defined as:
Where <em>m</em> is the mass of the roller coaster car
<em>s</em> is the speed and <em>k</em> is the kinetic energy
We know that 
Then the kinetic energy of the roller coaster car is:
First, distribute the 2 across the parenthesis.
10-3v+9v=28
Combine like terms on the left.
10+6v=28
Start to get the numbers on the right and the v alone on the left by moving the 10 to the right.
6v=28-10
6v=18
Divide to get the v alone.
v=3
Hope that helps.
Im not sure if you need to find the area or de expression of how to find the AREA. but what you do if explain how you can find it by multiplying that will be 4.. and then also 4? Im not sure but you can try
15 624/1000 is it supposed to be sipplified?
