Flashcards: Work, Energy and Power

 Page 1


Work, Energy & Power
Flash cards
Page 2


Work, Energy & Power
Flash cards
Work done by a constant force (continued)
Work done by a constant force      during displacement of 
point of application of force is
Page 3


Work, Energy & Power
Flash cards
Work done by a constant force (continued)
Work done by a constant force      during displacement of 
point of application of force is
Work done by a constant force
W = F
x
(x
2
– x
1
) + F
y
(y
2
– y
1
) + F
z
(z
2
– z
1
)
Where
Page 4


Work, Energy & Power
Flash cards
Work done by a constant force (continued)
Work done by a constant force      during displacement of 
point of application of force is
Work done by a constant force
W = F
x
(x
2
– x
1
) + F
y
(y
2
– y
1
) + F
z
(z
2
– z
1
)
Where
The work is said to be positive if the angle between force and 
displacement is acute (? < 90 ° ) because
W = = F S cos ? and cos ? = (+)ve
when ? < 90º.
The positive work means that the external force supplies 
energy to the system or body.
Page 5


Work, Energy & Power
Flash cards
Work done by a constant force (continued)
Work done by a constant force      during displacement of 
point of application of force is
Work done by a constant force
W = F
x
(x
2
– x
1
) + F
y
(y
2
– y
1
) + F
z
(z
2
– z
1
)
Where
The work is said to be positive if the angle between force and 
displacement is acute (? < 90 ° ) because
W = = F S cos ? and cos ? = (+)ve
when ? < 90º.
The positive work means that the external force supplies 
energy to the system or body.
Negative Work
The work is said to be negative if the angle between force and 
displacement is obtuse (? > 90 °) because cos? = (–)ve
when ? > 90 °.
The negative work means that the force is extracting energy 
from the system.