Question

A sprinter speeds up to 3 m/s during the last 2 seconds of the race with an
acceleration of 0. 4 m/s 2 . What was the initial speed of the sprinter?

Answer 1

Answer:

The initial speed of the sprinter was 2.2 m/s

Explanation:

Constant Acceleration Motion

It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.

The following relation applies:

$v_f=v_o+at$

Where a is the constant acceleration, vo the initial speed, vf the final speed, and t the time.

The sprinter speeds up from an unknown initial speed to vf=3 m/s in t=2 seconds with an acceleration of $a=0.4~m/s^2$.

To find the initial speed, we solve the equation for vo:

$v_o=v_f-at$

Substituting the values:

$v_o=3-0.4*2$

$v_o=3-0.8$

$v_o=2.2~m/s$

The initial speed of the sprinter was 2.2 m/s