certain force acting on a 20 kg mass changes its velocoty from 5m/to 2m/s calculate the work done
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-Mass of an object m= 20 kg,Initial velocity u = 5m/sand final velocity v = 2m/s
.·. Initial kinetic energy of object E1 = ½ mu²= ½ x 20 x (5)² = 250 J
And final kinetic energy of object E2 = ½ mv²= ½ x 20 x (2) ² = 40 J
.·. Loss in kinetic energy = E1 – E2 = 250 – 40 = 210 J
Work done by the force W = Change in kinetic energy = -210 J
The negative sign of work shows that there is decrease in kinetic energy of the mass.
.·. Initial kinetic energy of object E1 = ½ mu²= ½ x 20 x (5)² = 250 J
And final kinetic energy of object E2 = ½ mv²= ½ x 20 x (2) ² = 40 J
.·. Loss in kinetic energy = E1 – E2 = 250 – 40 = 210 J
Work done by the force W = Change in kinetic energy = -210 J
The negative sign of work shows that there is decrease in kinetic energy of the mass.
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mass= 20kg
u=5m/s
v=2m/s
k.e= m×(v-u)
= 1/2×20×(2-5)2
=1/2×20×(4-25)
=1/2×20×-21
=1/2×-420
=-210
u=5m/s
v=2m/s
k.e= m×(v-u)
= 1/2×20×(2-5)2
=1/2×20×(4-25)
=1/2×20×-21
=1/2×-420
=-210
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