Question

By application of a constant foree for 10 seconds, the velocity of an object of mass 20 kg changes tror

15 ms to 30 mis. Calculate the magnitude of the force applied​

Answer 1

see, first we should understand, what is the area of force-time graphs shows. It's the impulse. And impulse is equals to change in momentum.

first find impulse,

impluse = area

            =((1/2)×2×10)+ (2×10)+ ((1/2)×(10+20)×2)+((1/2)×4×20)

            =10+20+30+40

            =100 N-s

now, impulse = change in momentum

                     =m×v - m×u

where v= final velocity and u =initial velocity =0

so, 100 = 2×v  

⇒v = 50 m/s

hope this will help you

I hope it is clear

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