Answer:
Speed is a scalar quantity it has only magnitude. So in the given scenario the student actually described about the velocity.
Explanation:
In this situation, student is describing that the speed is -10 m/s. The speed with the negative sign is wrong because speed is a scalar quantity and scalar quantities have only magnitude, they do not have direction. So, his statement is wrong because he is describing the speed with the negative sign.
And also we know that velocity is a vector quantity, so it has magnitude as well as direction also. So in this situation, the student is actually want to describe the velocity because he is mentioning the magnitude in a particular direction.
The basic laws of physics<span> fall into two categories- classical </span>physics<span> that deals with the observable world, and atomic </span>physics<span> that deals with the interactions between elementary and sub atomic particles</span>
Answer: 
Explanation:
Given
Length of the race track 
the radius of curvature of the track 
time taken to run on track is 
Speed of runner is

Centripetal acceleration is

Answer:
probably liquid cause it can be contained easily