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## Homework Statement

A golfer rides in a golf cart at a speed of 3.10 m/s for 29.0 s. She then gets out of the cart and starts walking at an average speed of 1.20 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 2.10 m/s?

## Homework Equations

time = distance x avg. speed

## The Attempt at a Solution

Taking the distance traveled from the riding -

3.10 m/s x 29.0 s = 90 m

Tried numerous ways such as taking another 90m and using the 1.20 as a given

Problem 2

## Homework Statement

A sprinter explodes out of the starting block with an acceleration of +3.5 m/s2, which she sustains for 1.2 s. Then, her acceleration drops to zero for the rest of the race.

(a) What is her velocity at t = 1.2 s.

(b) What is her velocity at the end of the race?

## Homework Equations

Avg. Veloctiy = displacement/elapsed time

Avg. Accel. = Change in veloc./elapsed time

## The Attempt at a Solution

(a) 3.5 m/s^2 x 1.2 s = 4.2 m/s

(b) I believe that you would have to use -3.5 because of the decrease in acceleration but I can't seem to know how to get anything or figure anything out after that.