Question

A force of 10 N, acting on a body of mass 5 kg, changes its velocity from 10 ms -1 to 15 ms-1 . Determine the time for which the force acts.​

Answer 1

Solution

Given :-

• Force (F) = 10N
• Mass (m) = 5 kg
• initial velocity (u) = 10 m/s
• last velocity (v) = 15 m/s

Find

• Required time .

Explanation

Using Formula

$\boxed{\underline{\tt{\red{\:F\:=\:ma}}}}$

Where,

• F = Force
• m = mass of object
• a = acceleration of object

Now, keep all required values

We get,

==> 10 = 5 × a

==> a = 10/5

==> a = 2 m/s²

Now, we calculate time , which the force act

Using Formula

$\boxed{\underline{\tt{\red{\:v\:=\:u+at}}}}$

where,

• v = last velocity of object
• u = initial velocity of object
• a = acceleration of object
• t = time taken by object

Now, keep all required values

we get,

==> 15 = 10 + 2t

==> 2t = 15 - 10

==> 2t = 5

==> t = 5/2

==> t = 2.5 sec.

Hence

• Required time will be 2.5 sec.

___________________________

Some Point

(1)

★ Equation of Motion

• v = u + at
• s = u.t +(at) 1/2
• v² = u² + 2as

Where,

• u = initial velocity
• v = constant velocity
• a = acceleration
• s = Displacement
• t = time

______________________________

(2)

Newton's second low,

• Newton's second law of motion describes the relationship between an object's mass and the amount of force needed to accelerate it.

where,

• F = acting Force on object
• m = mass of object
• a = acceleration of object

___________________

Answer 2

Solution

Given :-

• Force (F) = 10N
• Mass (m) = 5 kg
• initial velocity (u) = 10 m/s
• last velocity (v) = 15 m/s
• Find
• Required time .

Explanation

• Using Formula

f=ma

Where,

• F = Force
• m = mass of object
• a = acceleration of object

Now, keep all required values

We get,

==> 10 = 5 × a

==> a = 10/5

==> a = 2 m/s²

Now, we calculate time , which the force act

Using Formula

where,

• v = last velocity of object
• u = initial velocity of object
• a = acceleration of object
• t = time taken by object

Now, keep all required values

we get,

==> 15 = 10 + 2t

==> 2t = 15 - 10

==> 2t = 5

==> t = 5/2

==> t = 2.5 sec.

Hence

Required time will be 2.5 sec.

___________________________

Some Point

(1)

★ Equation of Motion

v = u + at

s = u.t +(at) 1/2

v² = u² + 2as

Where,

• u = initial velocity
• v = constant velocity
• a = acceleration
• s = Displacement
• t = time

______________________________

(2)

Newton's second low,

Newton's second law of motion describes the relationship between an object's mass and the amount of force needed to accelerate it.

where,

F = acting Force on object

m = mass of object

a = acceleration of object

___________________