Question

An object of 2kg is placed at rest how much force must be applied on it so that a Velocity of 4m/s may be produced in 4s.​

Answer 1

Explanation:

Given:

• Mass of object, m = 2 kg
• Initial velocity of object, u = 0
• Final velocity required, v = 4 m/s
• Time for which force is to be applied, t = 4 s

To Find:

• Force to be applied on the object, F = ?

• Formulae required :

• First equation of motion

       v = u + a t

Newton's second law of motion

      F = m a

[ Where v is final velocity, u is initial velocity, a is acceleration, t is time taken, F is force applied and m is mass of object ]

Solution :

Using first equation of motion

→ v = u + a t

→ 4 = ( 0 ) + a ( 4 )

→ a = 4 / 4

→ a = 1 m/s²

Using Newton's second law of motion

→ F = m a

→ F = ( 2 ) ( 1 )

→ F = 2 N

Hence,

A force of 2 Newtons will be required .

Answer 2

Answer :

➥ Force applied on an object = 2 N

Given :

➤ Mass of an object (m) = 2 kg

➤ Final velocity of an object (v) = 4 m/s

➤ Time taken by an object (t) = 4 sec

To Find :

➤ Force applied on an object (F) = ?

Required Solution :

Note :

→ Initial velocity is 0 m/s because an object is placed at rest.

Now, we have also a Initial velocity of an object,

• Initial velocity of an object (u) = 0 m/s

✒ To find the Force applied on an object, first we need to find the Acceleration of an object, then after we will find the Force applied on an object.

We can find Acceleration of an object by using the first equation of motion which says v = u + at

Here, $\:$

• v is the final velocity in m/s.
• u is the initial velocity in m/s.
• a is the Acceleration in m/s².
• t is the Time taken in second

✎ So let's calculate Acceleration (a) !

⇒ v = u + at

⇒ 4 = 0 + a × 4

⇒ 4 = 0 + 4a

⇒ 4 - 0 = 4a

⇒ 4 = 4a

⇒ 4/4 = a

⇒ 1 = a

⇒ a = 1 m/s²

Now, we have, Mass of an object and Acceleration of an object,

• Mass of an object = 2 kg
• Acceleration of an object = 1 m/s²

We can find Force applied on an object by using the second law of Newton which says F = ma

Here,

• F is the Force in N.
• m is the mass in kg.
• a is the Acceleration in m/s².

✎ So let's find force (F) !

⇛ F = ma

⇛ F = 2 × 1

⇛ F = 2 N

║Hence, the force applied on an object is 2 N.║