Roberto has twice the mass his sister Mary has (see above) but runs at the same velocity as Mary. Will his kinetic energy be twice as much? Show your work. Marys Mass is 40kg

1. Mary has 20 joules of Kinetic energy

2. Yes his kinetic energy be twice as much

3. If Roberto runs twice as fast, his Kinetic energy will be 4 times as much

4. 16875 Joules

5. 5.77 m/s

6. 8 kg

7. 345600 J

Explanation:

The formula for Kinetic Energy is given as

We will apply this in solving all the problems below using the parameters provided by each problem.

1. Mary's Kinetic Energy will be equal to

2a. If Roberto has twice Mary's mass, his mass will be 80 kg.

His K.E will be

2b. If Roberto runs twice as fast, his kinetic energy will be . This is four times its initial value

4.

5.

6.

7.