Question

calculate the amount of force
required to change the speed of a body of mass 2kg from 18km/he to 54km/hr in 5 seconds​

Answer 1

Answer:

4N

Explanation:   From above figure  

A→B

u = 4m/s             v=0            t=2sec            a=?

v=u+at

0=4+a(2)

a=−2m/s  

2

 

so,  

force = ma

=2×2=4N

Answer 2

Answer:

Explanation:

Solution,

Here, we have

Mass, m = 2 kg

Initial velocity, u = 18 km/h = 18 × 5/18 = 5 m/s

Final velocity, v = 54 km/h = 54 × 5/18 = 15 m/s

Time taken, t = 5 seconds

To Find,

Force required, F = ?

At first we have to find the acceleration,

According to the 1st equation of motion,

We know that,

v = u + at

So, putting all the values, we get

⇒ v = u + at

⇒ 15 = 5 + a × 5

⇒ 15 - 5 = 5a

⇒ 10 = 5a

⇒ 10/5 = a

⇒ a = 2 m/s²

Here, the acceleration is 2 m/s².

According to Newton's 2nd law,

We know that,

F = ma

So, putting all  the values, we get

⇒ F = ma

⇒ F = 2 × 2

⇒ F = 4 Newtons

Hence, the force  required to change the speed is 4 Newtons.