1) A 0.11-kg baseball traveling in a horizontal direction with a speed of 19 m/s
ID: 2056650 • Letter: 1
Question
1) A 0.11-kg baseball traveling in a horizontal direction with a speed of 19 m/s hits a bat and is popped straight up with a speed of 15 m/s.(a) What is the change in momentum (magnitude and direction) of the baseball?
magnitude kg · m/s
direction ° above the horizontal and toward the pitcher
(b) If the bat was in contact with the ball for 33 ms, what was the average force of the bat on the ball?
magnitude N
direction
2) A BMW of mass 2.6 103 kg is traveling at 43 m/s. It approaches a 1.2 103 kg Volkswagen going 26 m/s in the same direction and strikes it in the rear. Neither driver applies the brakes. Neglect the relatively small frictional forces on the cars due to the road and due to air resistance.
(a) If the collision slows the BMW down to 34 m/s, what is the speed of the VW after the collision?
m/s
(b) During the collision, which car exerts a larger force on the other, or are the forces equal in magnitude?
a.BMW exerts the larger force.
b.Forces are equal in magnitude.
c.Volkswagen exerts the larger force.
Explanation / Answer
Ok then, Q2
a) all we have to do is apply the law of conservation of momentum
pi = pf
Before both cars have momentum and after both cars still have momentum. I'll use Mb to be mass of bmw and Mv to be mass of VW, vb to be velocity of bmw and vv to be velocity of VW.
(Mb)(vbi) + (Mv)(vvi) = (Mb)(vbf) + (Mv)(vvf)
(2.6*10^3kg)(43m/s) + (1.2*10^3)(26m/s) = (2.6*10^3kg)(34m/s) + (1.2*10^3kg)(vvf)
vvf = 45.5m/s
b) Anytime we have an interaction between objects, Newton's 3rd law says that those objects exert equal and opposite forces on each other. Therefore the answer is B.
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