Question

With an example each, explain when is work said to be a)positive b)negative c)zero(

Answer 1

it is
answer of your questions

Answer 2

Answer:

POSITIVE WORK: The work done on an object is said to be positive work when force and displacement are in same direction.

Example: When an object moves on horizontal surface, force and displacement acts in same direction. So, work done is positive.

NEGATIVE WORK: The work done is said to be negative work when force and displacement are in opposite direction.

Example: When an object is thrown upwards,the force of gravity is in downward direction whereas displacement acts in upward direction.  

ZERO WORK: The work done is said to be zero when force and displacement are perpendicular to each other or when either force or displacement is zero.

Example: When we hold an object and walk, the force acts in downward direction whereas displacement acts in forward direction.