A man walking with a suitcase held in his hand .
A)why is no work done on the suitcase if the man is walking on a horizontal platform?
B)why is work said to be done if the man is coming a staircase ?
Dear Student
(A) A man holding a suitcase in his hand and walking on a horizontal platform.
Net force acting on the suitcase is zero.
Work done on the suitcase by the man is zero.
Suitcase is not moved with respect to the man.
According to the definition of work done ,a body does a work only when it displaces from its position .It means that there should any displacement.
W = F.s
A man carrying a suitcase does not move i.e. s = 0
W = F.s
=F.0
W = 0
(B)
Work is done when carrying a suitcase and climbing the stairs.
As a force is acting (gravity) and the displacement is not perpendicular to the direction of the force, so there will be negative work done.
The work done by a man in climbing the stairs with suitcase is negative since the man is moving against the force of gravity acting downward. Work is said to be done , when a force or its component causes displacement in the direction of force.
Regards
(A) A man holding a suitcase in his hand and walking on a horizontal platform.
Net force acting on the suitcase is zero.
Work done on the suitcase by the man is zero.
Suitcase is not moved with respect to the man.
According to the definition of work done ,a body does a work only when it displaces from its position .It means that there should any displacement.
W = F.s
A man carrying a suitcase does not move i.e. s = 0
W = F.s
=F.0
W = 0
(B)
Work is done when carrying a suitcase and climbing the stairs.
As a force is acting (gravity) and the displacement is not perpendicular to the direction of the force, so there will be negative work done.
The work done by a man in climbing the stairs with suitcase is negative since the man is moving against the force of gravity acting downward. Work is said to be done , when a force or its component causes displacement in the direction of force.
Regards