Question

Question 4 plzzzzzz,,,zzzzzzzzzzzz

Answer 1

Workdone =1/2m(v^2-u^2)

Answer 2

Here, given mass = 20 kg

initial velocity (u) = 5 m/sec

final velocity (v) = 2 m/sec

time (t)= 1sec

so , from first equation of motion

v= u+ at

or, a= ( v- u) / t

a= ( 2 ms-¹ - 5 ms-¹) / 15

a= - 3 ms-²

therefore, from third equation of motion

v²- u²= 2as

= ( 2ms -1 )² - ( 5ms-¹) ²

= 2× (-3ms-²) ×5

= -21 m²s² = -6ms-²× 5

= s = 7/2 metre

therefore, we know ,

workdone= f × s

and , F = m× a

so, work = m× a× s

= 20 kg × ( -3ms-²) × 7/2m

= - 210 joules

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