Question

If an object of mass 200g is travelling with a velocity of 14m/s and comes to rest in 2s . Find the unbalanced force which brings the object to the rest

Answer 1

Answer:

-1.4 Newtons

Explanation:

Given :

• Mass of the object = m = 200 grams = 0.2 kg

• Initial velocity = u = 14 m/s

• Final velocity = v = 0 m/s

• Time taken = t = 2 seconds

To find :

• The unbalanced force which brings the object to rest

Force = m(v-u) / t

Force = 0.2(0-14)/2

Force = 0.2×-14/2

Force = -2.8/2

Force = - 1.4 Newtons

The unbalanced force acting on the body is equal to - 1.4 Newtons

Note : Force = mass × Acceleration (Acceleration : (v-u) /t)

Answer 2

Answer :

Given that object of mass 200g is travelling with a velocity of 14 m/s comes to rest in 2 s.

We have to find force which brings it to rest.

From data we have :

Mass (M) = 200 g = 200/1000 = 0.2 kg

Initial velocity (u) = 14 m/s

Final velocity (v) = 0 m/s

Time (t) = 2 s

Using 1st equation of motion :

→ v = u + at

→ 0 = 14 + a × 2

→ -14 = 2a

→ a = -14/2

→ a = -7 m/s²

Now using Newton's 2nd law :

→ Force = Mass × Acceleration

Substituting values,

→ Force = 0.2 × (-7)

→ Force = -1.4

→ Force = -1.4 N

As the force is negative, so that means force is acting against the motion of body.

∴ Force which takes it to rest = -1.4 Newtons.