Question

Find the time for which a force of 6*10-4 should act on a body of mass 1 kg at rest in order to produce in it a velocity of 3m/s

Answer 1

Explanation:

t=6*10-4*3*1000

t=60sec

Answer 2

Answer:

5000 seconds is needed to reach the velocity 3 m/s .

Explanation:

Provided that:

Force applied (F) = 6 × 10^-4 Newton

Mass of the body (m) = 1 Kg

Initial velocity (u) = 0 m/s

Final velocity (v) = 3 m/s

Let the time is taken to achieve the velocity;

(t) = t sec

Now from Newton's laws of motion (2nd law) we know that: F = m.a ... equation (i)

From this equation we can calculate the acceleration (a) of the body;

$F = m.a \: \: ... equation (i) \\ a = \frac{F}{m} \\ so \: \: a = \frac{6 \times {10}^{ - 4} }{1} \: m. {sec}^{ - 2} \\ = 6 \times {10}^{ - 4}\: m. {sec}^{ - 2}$

Hence we get the acceleration:

(a) = 6×10^-4 m/sec^2

From Kinematics we know that:

$v = u + a.t \: \: ...equation(ii)$

From this equation we can calculate the time taken by body to reach the velocity 3 m/s ;

$v = u + a.t \\ or \: t = \frac{v - u}{a} \\ or \: t = \frac{3 - 0}{6× {10}^{ - 4} } \:sec\\ = 5000\: sec$

Hence we get t = 5000 seconds is needed to reach the velocity 3 m/s .

This is the required answer.