Which of the following are examples of work being done on an object? Choose the 4 that apply.
a
holding a 50 kg barbell over your head
b
wind blowing against a tree
c
pushing a grocery cart through the store
d
lifting a rock off the ground
e
carrying a box up a flight of stairs.
f
pushing on a car that will not move
g
lifting a bag of groceries
The examples of work being done on an object are:
a) holding a 50 kg barbell over your head
c) pushing a grocery cart through the store
d) lifting a rock off the ground
e) carrying a box up a flight of stairs.
HOLDING a barbell ---> no motion=no work
LIFTING a bag---> YES, force and motion in direction of the force
Apologies for the confusion. You are correct. Holding a barbell over your head does not involve any motion and therefore does not involve work. So, the correct examples of work being done on an object are:
c) pushing a grocery cart through the store
d) lifting a rock off the ground
e) carrying a box up a flight of stairs.
g) lifting a bag of groceries