Question

an object of mass 7kgs moving with 14m/sec. A force is applied so that in 28 secs, it attains a velocity of35m/sec. What is the force applied on the object?​

Answer 1

Given :

• Initial velocity, u = 14 m/s

• Final velocity, v = 35 m/s

• Time, t = 28 seconds

• Mass of an object, m = 7 kg

To find :

• Force applied on the object, F

According to the question,

By using Newtons first equation of motion we will find acceleration then by using F = ma we find force applied on the object.

➞ v = u + at

Where,

• v = Final velocity
• u = Initial velocity
• a = Acceleration
• t = Time

➞ Substituting the values,

➞ 35 = 14 + a × 28

➞ 35 - 14 = 28a

➞ 21 = 28a

➞ 21 ÷ 28 = a

➞ 0.75 = a

So,the acceleration is 0.75 m/s².

Now,

➞ Force = Mass × Acceleration

Or,

➞ F = ma

➞ F = 7 × 0.75

➞F = 5.25 N

So,the force applied on the object is 5.25 Newton.

Answer 2

Answer:

Given :-

• An object of mass 7kg moving with 14 m/s.
• A force is applied so that in 28 secs, it's attains a velocity of 35 m/s.

To Find :-

• What is the force applied on the object.

Formula Used :-

❶To find acceleration, we know that,

$\boxed{\bold{\large{v\: =\: u\: +\: at}}}$

❷ To find force, we know that,

$\boxed{\bold{\large{F\: =\: ma}}}$

where,

• v = Final velocity
• u = Initial velocity
• a = Acceleration
• t = Time
• F = Force
• m = Mass

Solution :-

❶ First, we have to find the acceleration,

Given :

• Mass = 7 kg
• Initial velocity = 14 m/s
• Final velocity = 35 m/s
• Time = 28 seconds

According to the question by using the formula we get,

⇒ 35 = 14 + a(28)

⇒ 35 = 14 + 28a

⇒ 35 - 14 = 28a

⇒ 21 = 28a

⇒ $\dfrac{\cancel{21}}{\cancel{28}}$ = a

⇒ 0.75 = a

➠ a = 0.75 m/s²

❷ Now, we have to find the force,

Given :

• Mass = 7 kg
• Acceleration = 0.75 m/s²

According to the question by using the formula we get,

↦ F = 7 × 0.75

➥ F = 5.25 N

$\therefore$ The force applied on the object is 5.25 N .