Q.9. A body with a mass of 1 kg is accelerated by a force of [tex]2 \, N[/tex]. What is the velocity of this body after [tex]5.0 \, s[/tex] of motion?



Answer :

To determine the velocity of a body after a given time when accelerated by a constant force, follow these steps:

1. Identify the given data:
- Mass ([tex]\( m \)[/tex]) of the body: [tex]\( 1 \, \text{kg} \)[/tex]
- Force ([tex]\( F \)[/tex]) applied: [tex]\( 2 \, \text{N} \)[/tex]
- Time ([tex]\( t \)[/tex]) of motion: [tex]\( 5.0 \, \text{s} \)[/tex]

2. Calculate the acceleration:
- According to Newton's second law of motion, force is the product of mass and acceleration:
[tex]\[ F = ma \][/tex]
Solving for acceleration ([tex]\( a \)[/tex]):
[tex]\[ a = \frac{F}{m} = \frac{2 \, \text{N}}{1 \, \text{kg}} = 2 \, \text{m/s}^2 \][/tex]

3. Determine the initial velocity:
- Assuming the initial velocity ([tex]\( u \)[/tex]) is [tex]\( 0 \, \text{m/s} \)[/tex] (i.e., the body starts from rest).

4. Calculate the final velocity:
- Use the kinematic equation that relates initial velocity ([tex]\( u \)[/tex]), acceleration ([tex]\( a \)[/tex]), and time ([tex]\( t \)[/tex]) to the final velocity ([tex]\( v \)[/tex]):
[tex]\[ v = u + at \][/tex]
Substituting in the known values:
[tex]\[ v = 0 \, \text{m/s} + (2 \, \text{m/s}^2 \times 5.0 \, \text{s}) = 10 \, \text{m/s} \][/tex]

Therefore, the velocity of the body after [tex]\( 5.0 \)[/tex] seconds of motion is [tex]\( 10 \, \text{m/s} \)[/tex].