Kinematics. Suppose the x-velocity v_x of a car at any time t is given by the eq

Question

Kinematics. Suppose the x-velocity v_x of a car at any time t is given by the equation: v_x = 65 m/s + (0.75 m/s^3)t^2 (a) Find the change in x-velocity of the car in the time interval. (b) Find the average x-acceleration in this time interval. delta v = 7.5 m/s a avg = 45 m/s^2 delta v = 92 m/s a avg = 7.5 m/s^2 delta v = 45 m/s a avg = 7.5 m/s^2 delta v = 92 m/s a avg = 15 m/s^2 Conservation of Linear Momentum. Two bump cars move toward each other colliding head-on on a frictionless track. Car A has a mass of 140.0 kg, and car B has a mass of 130.0 kg: both cars move with an initial speed of 12.0 m/s (approaching each). After they collide, Car B moves away with an initial velocity whose x component is + 15.0 m/s. What is the final velocity of Car A? -13.9 m/s 13.1 m/s -17.1 m/s -13.1 m/s

Explanation / Answer

17)a) Velocity at t=2 seconds = 65+(0.75*22) = 68m/s

Velocity at t=8 seconds = 65+(0.75*82) = 113 m/s

Change in velocity = 113-68 = 45 m/s

b) average acceleration = 45/(8-2) = 7.5m/s2

Third option is correct

18) Initial moment of system = (140*12)+(130*-12) = 120kg-m/s

Let velocity of car a be v

Final momentum of system = (130*15)+(140*v)

From conservation of momentum,

(130*15)+(140*v) = 120

v= -13.1 m/s

4th option is correct

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