Question

Give reason:a) A horse and a dog are running with the same speed. One of them has more kinetic energy than the otherb)A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work.

Answer 1

A• horse and dog are running with same speed but horse has greater kinetic energy because its mass is greater than dog as velocities same.. kinetic energy depends on both mass and velocity if the velocity is constant and the mass of horse is Greater then that of dog therefore more the mass of horse more is the kinetic energy

B•. work= force× displacement
in case of teacher ,
both the force and displacement does not equal to zero therefore some work is done
while in case of student
force doesn't equal to zero but displacement is zero.. therefore work done by the student is zero