Question

A runner accelerates to 4.2 m/s2 for 10 seconds before winning the race. How far did he/she run?

Answer 1

She run the distance of 42metres

Answer 2

Answer:

Runner will run for 210m

Step by Step Explanation:

According to Newton's first of motion,

Vf=Vi+at

Given is

the speed with which runner is running will be Vi, he is running with accelertion a=4.2m/s2 fot time t=10sec

Vf will be 0 because runner will stop after winning the race

we will find Vi from equation 1,

Vi=Vf-at

   = 0- 4.2*10

   =-42 m/s  (negative sign is showing decceleration)

So, Vi=42 m/s

According to Newton's third of motion,

2aS= Vf^2-Vi^2

S is distance, he will cover before stopping,

2(4.2)S= 0- 42^2

S=1764/8.4

S=210m

Runner will run for 210m