A particle of mass 120 g moving at speed of 750 cm/s is acted upon by a variable force opposite to its direction of motion. If the velocity of the particle becomes 250 cm/s along the direction of force, find the value of time 't' for which acted.

Explanation

To solve the problem, we will follow these steps:

### Step 1: Convert the mass and velocities to standard units
- Given mass \( m = 120 \, \text{g} \)
- Convert mass to kilograms:
\[ m = 120 \, \text{g} = 120 \times 10^{-3} \, \text{kg} = 0.12 \, \text{kg} \]
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