How much work is done.....?

Question

A 73 gram particle is moving to the left at 19 m/s. How much work must be done on the particle to cause it to move to the right at 51 m/s ? answer in joules

Answer 1

Since Work=.5(m)v^2

we know the energy of the system is:

.5*.073*19^2=13.1765 Joules

We need to get it going to opposite direction at 51m/s.  The energy of the final system is:

.5*.073*51^2=94.9365 Joules

Work Required=94.9365+13.1765= 108.113 Joules

Ans=108.113 Joules

Enjoy

Edit:  The Hamburglar used the wrong value for weight, he used 78 grams instead of 73.

Answer 2

Work to get the particle to move 0m/s:

W = 1/2*0.073*(19^2) = 13.18

Work to get the particle to move to 51m/s

W = 1/2*0.073*(51^2) = 94.9

Together: 13.18+94.94 = 108.1 J

Edit, sorry I misread the question, I changed the answer.