# Physics

posted by .

Two brothers are jogging, Josh and Drake. Josh has 1/2 the KE of Drake. Also, he is twice the mass of Drake. Plus, Josh had to increase his speed by 1.35 meters/second to achieve the same kinetic energy of Drake. What is the initial velocity?

• Physics -

JoshKE=1/2DrakeKE
1/2Mj vj^2=1/4 Md Vd^2
1/2 2Md Vj^2=1/4 Md Vd^2

Vj^2=1/4 Vd^2

Vj= 1/2 Vd

but Vj+1.35 yields..
1/2 *2Md(Vj+1.35)^2=1/2 Md Vd^2
2(Vj+1.35)^2=Vd^2
finally

2(Vj+1.35)^2=4Vj^2
Vj+1.35=Vj sqrt2
Vj=1.35/.414=
check all that.

## Similar Questions

1. ### Math

Josh and Mike live 13 miles apart. Yesterday Josh started to ride his bicycle toward Mike's house. When they met, Josh had ridden for twice the length of time as Mike and at 4/5 of Mike's rate. How many miles had Mike ridden when they …
2. ### English

I checked the sentences myself.There were spelling mistakes to correct. I need to prepare this listening activity taken from a course book (again). I just want to be sure that everything is OK. 1) Travel and expeditions were much in …
3. ### Personal finance

Josh has decided to take a course at the local community college that could help him get a promotion at work. The course begins at 5pm and goes until 9pm on monday nights. Josh normally works until 5pm each day, but because of the …
4. ### Physics

Your friend Josh tells you that he spends less on gas in the winter than in the summer. He also says that he has to fill up his tank less often in the winter. (a) Which of the following are possible hypotheses that can be formed from …
5. ### Microsoft word

Elisa and Josh need to access General Help. Elisa will press the F1 key. Josh will click on ?
6. ### Microsoft word

Elisa and Josh need to access General Help. Elisa will press the F1 key. Josh will click on ?
7. ### Math

The ratio of Mon's pencils to Josh's pencil id 5:7. Josh has 18 pencils more than Mon. If Josh gives 9 pencils to Mon, what will be the new ratio of Mon's pencils to Josh's pencils?
8. ### Math

Drake has 5 baskets of fruit. Each basket has 12 plums and 14 apricots. How many pieces of fruit does Drake have in the baskets?
9. ### math

eli is twice as old as josh, and ben is six years older than josh. the sum of their age is 50.how old is each person?
10. ### maths

The ratio of Mon's pencils to Josh's pencil id 5:7. Josh has 18 pencils more than Mon. If Josh gives 9 pencils to Mon, what will be the new ratio of Mon's pencils to Josh's pencils?

More Similar Questions