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A block of mass 10 kg, moving in x direction with a constant speed of 10 ms–1, is subject to a retarding force F = 0.1 × J/m during its travel from x = 20 m to 30 m. Its final KE will be :
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- 450 J
- 275 J
- 250 J
- 475 J
Correct Option: D
From, F = ma
| a = | = | = 0.01x = V | ||||
| m | 10 | dx |
= 4.5 – 2 = 2.5
| m(V22 - V12) = 10 × 2.5J = -25 J | ||
| 2 |
| Final K.E. = | mv22 = | mv12 - 25 = | × 10 × 10 × 10 - 25 | |||
| 2 | 2 | 2 |
= 500 – 25 = 475 J
