Hello, 1. The question states: Which of the following gives the averagevelocity

Question

Hello,

1. The question states: Which of the following gives the averagevelocity of an athlete running on a circular track with acircumference of 1/2 km, if that athlete runs 1 km in 4minutes?

The solution states: It would be 0 m/s because the runner is on acircular track of ? km, the runner will end up where he/she began.This is zero displacement and zero velocity.

^^^ I did not understand this solution. May someone simplify this?I don't understand how zero displacement means zero velocityeither.

2. Also, as a short part two: When is G( gravitationconstant) negative? (= -9.8 m/s^2)? Is it when a ball is thrownupward?

Explanation / Answer

Question is :           Whichof the following gives the average velocity of an athlete runningon a circular track with a circumference of 1/2 km, if that athleteruns 1 km in 4 minutes?
Answer is :             We know that velocity is :                                 v = change in displacement / time                                     = s / t                                     = ( sfinal - sinitial ) / t          As thetrace is a circular track with radius 1/2 km , herefinal and initial positions becomes equal .           Hence  displacement s = 0         velocity ( v) = 0 / t = 0 m/s (2)          Universal gravitational constant never be negative .              Its value is :   G = 6.624  x 10-11   N - m2 /kg2          Accelerationdue to gravity (g)changes in sign with the direction of theobject. If the Object is falling towards the Earth (g) ispositive. If the Object is thrown upwards that is moving away from theEarth , value of "g" is negative. Hope this helps u!

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