Question

m=20kg
u= 5 m/s F=40N
t = 4s
mv= ? find mv​

Answer 1

Answer:

Explanation:

Given,  

Mass.m = 20 kg.

Initial velocity, u=5m/s

Final velocity, v=2m/s

Work done = change in K.E.

W=  

2

1

​  

.mv  

2

−  

2

1

​  

mv  

2

 

=  

2

1

​  

m(v  

2

−u  

2

)

=  

2

1

​  

.20(2  

2

−5  

2

)

=  

2

1

​  

.20(4−25)

=−10.(21)

=−210J

∴ Here, the negative sign implies the retarding  

nature of the applied force.