Question

What is the kinetic energy of a 78kg object moving at a velocity of 2.5m/s

Answer 1

`\boxed {\boxed {\sf 243.75 \ J }}`

Step-by-step explanation:

Kinetic energy is energy an object has due to motion. The formula is:

`KE=\frac {1}{2}mv^2`

The mass of the object is 78 kilograms and the velocity is 2.5 meters per second.

`m= 78 \ kg \\v= 2.5 \ m/s`

Substitute the values into the formula.

`KE= \frac {1}{2} (78 \ kg)*(2.5 \ m/s)^2`

Solve according to PEMDAS: Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction. Solve the exponent first.

• (2.5 m/s)²= 2.5 m/s * 2.5 m/s = 6.25 m²/s²

`KE= \frac {1}{2}(78 \ kg)*6.25 \ m^2/s^2`

Multiply all three numbers together.

`KE=39 \ kg * 6.25 \ m^2/s^2\\`

`KE=243.75 \ kg*m^2/s^2`

1 kilogram meter squared per second squared is equal to 1 Joule. So, our answer of 243.75 kg *m²/s² is equal to 243.75 Joules.

`KE=243.75 \ J`

The object has 243.75 Joules of kinetic energy.