Homework Answers

A 1450-kg

 car is traveling with an initial speed of 24.0 m/s.

Determine the car's speed after −1.90 ✕ 10⁵ J

 of net work is done on the car.

Question 5.2b:

A 11.8-kg

 box is sliding across a horizontal floor. It has an initial speed of 1.45 m/s

 and the only force acting on it is kinetic friction with magnitude f_k = 2.65 N.

Determine the distance the box will travel before coming to rest.

A toy car having mass m = 1.10 kg

 collides inelastically with a toy train of mass M = 3.80 kg.

 Before the collision, the toy train is moving in the positive x-direction with a velocity of V_i = 2.45 m/s

 and the toy car is also moving in the positive x-direction with a velocity of v_i = 4.95 m/s.

 Immediately after the collision, the toy car is observed moving in the positive x-direction with a velocity of 2.25 m/s.

(a) Determine V_f, the final velocity of the toy train.

(b) Determine the change ΔKE

 in the total kinetic energy. Assume friction and the rotation of the wheels are not important so that they do not affect ΔKE.

An object of mass 2 kg is launched at an angle of 30^o above the ground with an initial speed of 40 m/s. Neglecting air resistance , calculate:

i. the kinetic energy of the object when it is launched from the  the ground.

ii. the maximum height attained by the object .

iii. the speed of the object when it is 12 m above the ground.

Bung Tie is running along a straight line. Assume that he starts from rest from point A and accelerates uniformly for T s, before reaching a speed  of 3 m/s. He is able to maintain this speed for 5 s. After that, it takes him 6 s to decelerate uniformly to come to a stop at point B. 

i. Sketch a speed versus time graph based on the information given above.

ii.Find the value of T if the distance between A and B is 100 m.

iii. Determine the deceleration.

A car accelerates from zero to a speed of 36 km/h in 15 s.

i.

Calculate the acceleration of the car in m/s².

ii.

If the acceleration is assumed to be constant, how far will the car travel in 1 minute ?

iii.

Calculate the speed of the car after 1 minute.