Hello, dbakeg00!

You're expected to know that: .

We have: .A body moves in such a way that its position at time is given by: . , wherenis a constant.

(a) Find when the velocity is doubled from the 5th to the 10th second.

Then: .

is twice

Therefore: .

We have: .(b) Find when the velocity is numerically equal to the acceleration at the end of the 10th second.

Then: .

These two quantities are equal: .

Divide by

. . . . . Therefore: .