Question

If a net force of 7 N was constantly applied on 400 g object at rest, how long will it take to raise its velocity to 80 m/s?

Answer 1

We can first find the acceleration as we know the force and mass
Also we know u=0 and v= 80m/s
So, by applying eq of motion

V = u + at
We can find "t" which will come out to be 4.5 s

Answer 2

Answer:

Time, t = 4.57 seconds

Explanation:

Given that,

Net force acting on the object, F = 7 N

Mass of the object, m = 400 g = 0.4 kg

Initial velocity of the object, u = 0

Final velocity of the object, v = 80 m/s

Let t is the time taken to reach its final velocity. The net force acting on the object is given by :

F = m a

$F=m\times \dfrac{v-u}{t}$

$F=m\times \dfrac{v}{t}$

$t=\dfrac{mv}{F}$

$t=\dfrac{0.4\times 80}{7}$

t = 4.57 s

So, the time taken by the object is 4.57 seconds. Hence, this is the required solution.