Air vessels in reciprocating pump are used to : 

The work done in physics is defined:
(a)By force applied on an object, which cannot displace the object
(b)By displaced object
(c)By force applied to the object
(d) All the above

A boat full of iron nails is floating on water in a lake. When the iron nails are removed, the water level ______.

The product of mass and acceleration _____:

Which among the following is the correct statement?
A. When an object is thrown upwards, then in any case whether going upwards or coming downwards its speed will remain the same. 
B. The weight of any object cannot be zero.