Question

An object of 360grams moving with 35m/s changes to 70m/s in 5sec.find the force?

Answer 1

Answer:

m= 0.36kg

u= 35m/s

v= 70m/s

t= 2sec

so a = v-u/t

a= 35/2= 17.5m/s^2

f= ma

= 0.36× 17.5

= 6.3Newton

Answer 2

» To Find :

The force applied on the object .

» Given :

• Mass of the object $\rightarrow m = 360 g = 0.36 kg$

• Intial velocity $\rightarrow u = 35ms^{-1}$

• Final velocity $\rightarrow v = 70ms^{-1}$
• Time taken $\rightarrow t = 5s$

» We Know :

First law of motion :

$\mathtt{\underline{\boxed{v = u + at}}}$

Where ,

• v = Final velocity
• u = Intial velocity
• a = Acceleration
• t = Time taken

Force :

$\mathtt{\underline{\boxed{F = ma}}}$

where,

• F = Force applied
• m = Mass
• a = Acceleration

» Concept :

To Find the force applied , first we have to find the acceleration produced by the object as :

$\boxed{f \propto a}$

For finding the acceleration :

• Intial velocity $\rightarrow u = 35ms^{-1}$
• Final velocity $\rightarrow v = 70ms^{-1}$

• Time taken $\rightarrow t = 5s$

We Know the formula :

$\mathtt{\underline{\boxed{v = u + at}}}$

Putting the value in the equation ,we get :

$\mathtt{\Rightarrow 70 = 35 + a \times 5}$

$\mathtt{\Rightarrow 70 - 35 = 5a}$

$\mathtt{\Rightarrow 35 = 5a}$

$\mathtt{\Rightarrow \dfrac{35}{5} = a}$

$\mathtt{\Rightarrow \cancel{\dfrac{35}{5}} = a}$

$\mathtt{\Rightarrow 7 ms^{-2} = a}$

Hence ,the acceleration produced by the object is $7 ms^{-2}$

Now by the acceleration produced and the mass of the object ,we can find the force applied .

» Solution :

• Mass = $0.36 kg$
• Acceleration = $7 ms^{-2}$

Formula for finding the acceleration produced :

$\mathtt{\underline{\boxed{F = ma}}}$

Putting the value of acceleration and mass in the formula ,we get :

$\mathtt{\Rightarrow F = 0.36 \times 7}$

$\mathtt{\Rightarrow F = 2.52 N}$

Hence, the Force applied is 2.52 N.

Additional information :

Second law of motion :

S = ut + ½at²

Third law of motion :

v² = u² + 2as

Formula for nth second :

s' = u + ½a(2n - 1)

Where ,

• v = final Velocity
• u = initial Velocity
• a = Acceleration
• t = time taken
• n = nth second
• s = displacement