Question

an external forces of 5N changes the velocity of a body of mass 2kg from 5 m/s second to 7 m/s the time for which force applied is
(a)0.9 second (b)1second
(c)0.8second (d)2seconds
explain by the process ​

Answer 1

Answer:

Brainliest Please

Explanation:

force = m(v-u)/t

5=2(7-5)/t

5=2(2)/t

5=4/t

5t=4

t=4/5

t=0.8

Answer 2

Answer :

Option (c) is correct

• (c) 0.8 seconds

Explanation :

Given,

An external force of 5 N changes the velocity of a body of mass 2 kg from 5 m/s to 7 m/s

• Force applied, F = 5 N
• initial velocity of body, u = 5 m/s
• final velocity of body, v = 7 m/s
• mass of body, m = 2 kg

to find,

• time for which force is applied, t = ?

Formula required,

• Newton's second law

         F = m a

• First equation of motion

       v = u + a t

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

Solution,

Using Newton's second law

→ F = m a

→ 5 = (2) × a

→ a = 5/2  m/s²

Using first equation of motion

→ v = u + a  t

→ 7 = (5) + (5/2) t

→ 7-5 = (5/2) t

→ 2 = (5/2) t

→ t = ( 2 × 2 ) / 5

→ t = 4 / 5

→ t = 0.8  s

therefore,

• Time for which force is applied is 0.8 seconds.