an object of mass 1 kg is lifted to a vertical height of 1m, the work done is
Answers
Explanation:
Unit of energy is Joules (J) or Kg m^2 /s^2.
Where
m = mass of the object = 1 kg
g = gravitational force on earth = 9.8 m/s^2
h = the height lifted = 1 m
E = mgh
= (1 kg) (9.8 m/s^2) (1m)
= 9.8 kg m^2 /s^2 0r 9.8 Jules
Therefore the energy required to lift the object of mass 1kg to the height 1 m is 9.8 Jules.
Given:
The mass of the object = 1 kg
The distance through which the object is lifted = 1 m
To Find:
The work done in lifting the object
Solution:
Work done = Force X Distance X cos ∅
where ∅ is the angle between the force and the distance
∴ WD = F s cos ∅
Force applied by gravity during the process is in the downward direction while the displacement of the box is upwards.
⇒ ∅ = 180
Hence, WD by gravity = (mg) . s . cos 180°
= - 9.8 J (taking g = 9.8m/s²)
The work done by the person is equal in magnitude but opposite in direction to the work done by gravity.