Question

Bob and joe have a class together at Kensington college. They leave the class at the same time. Bob goes to the library at 4 miles per hour, joe heads to the exact opposite direction at 2 miles per hour. How long will it be before the classmates are 2 miles apart .

Answer 1

For this case we can create the following schema

We can use the definition of distance:

x= vt

We can find the relative velocity:

`V_{\text{rel}}=4-2=2(mi)/(hr)`

And the distance between both is required to be 2 mi so then we can find the time like this:

`t=\frac{x}{v_{\text{rel}}}=(2mi)/((2mi)/(hr))=1hr`

Then the answer is:

1 hr