Answers

  • Brainly User
2016-03-23T00:59:32+05:30
We know the

Kinetic energy = 400 J 
Time=2 s
Initial velocity, u=0

 v = u + gt

v = 0 + 10 x 2 = 20 m/s
 
K =  \frac{1}{2} mv² = 400

 \frac{1}{2}  × m × 20² = 400

 m = 2 kg

The mass of the object is 2 kg. 
0
2016-03-23T05:40:36+05:30
{assuming g=10m/s}
Using the 1st eqn ,
V=u+gt
⇒v=0+10(2)
⇒v=20m/s.

KE=0.5mv²
⇒400=0.5m(400)
⇒m=2kg
                          
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