Bonus questions 35 15 Show your all calculations for full c

Bonus questions (3*5 = 15) Show your all calculations for full credit A 1400-kg car has a net forward force of 4500 N applied to it. The car starts from rest and travels in a horizontal highway. Ignore losses in kinetic energy because of friction and air resistance. What is kinetic energy? What is its speed after it has traveled 100 m? 60 kg ice skater moving a t 1.85 m/s in the +x direction collides with an 87.5 kg skater initially after collision two skaters move together for short period of time. Find the velocities of the collision. Find the total energy lost during this collision.

Solution

Applying work-energy theorem,

Work done by all forces = change in KE

(100 * 4500) = Kf - Ki

450000 = K - 0

K = 450000 J .........Ans (a)

(B) K = m v^2 /2

450000 = 1400 v^2 /2

v = 25.35 m/s

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Applying moemntum conservation for collision,

initial total momentum= final momentum

60 x 1.85   + 87.5 x 0 = (60 + 87.5)v

v = 0.75 m/s ........Ans(a)

(B) Ki = (60 x 1.85^2 / 2 ) + (87.5 x 0^2 /2 )

Ki = 102.675 J

after collision KE, Kf = (60 + 87.5) (0.75^2)/2 = 41.48 J

energy lost = KEi - KEf =102.675 - 41.48 = 61.2 J