Need help solving these problems 1. Which of the following is not one of the fou

Question

Need help solving these problems

1. Which of the following is not one of the four fundamental laws that have been found to hold in every experimental situation tested? A. Conservation of Energy C. Newton's second law B. Conservation of Momentum D. Conservation of electric charge 2. A 3 kg metal ball moves in the +x direction with a speed of 15 m/s, which of the following statements about its momentum is true A. The x component of its momentum is+ 45 kg m/s B. The x component of its momentum is 45 kg m/s C. The y component of its momentum is + 45 kg m/s The x component of its momentum is 5 kg m/s 3.4 3 kg metal ball initially moves in the x direction with a speed of 15 m/s. Then it hits a glass and bounce back, moves in the -x direction with a speed of 10 m/s. What is the change of its momentum? A. 15 kg m/s in the +x direction C 15 kg m/s in the -x direction B. 75 kg m/s in the +x direction D. 75 kg m/s in the -x direction 4. If the ball in contact with the glass for 0.05 seconds when it bounces, what is the magnitude of the average force that the glass applies on the ball? A. 300 N B 1500 N C. 0.75 N D. 3.75 N

Explanation / Answer

2.

Momentum is givenn by:

P = m*v

v = 15 m/sec in +x-direction

m = 3 kg

P = 15*3 = +45 kg m/sec, which is the x-component of momentum

Correct option is A.

3.

Change in momentum = dP = m*vf - m*vi

dP = 3*(-10) - 3*(+15) = -75 kg m/sec, negative sign means it in -x direction

Correct option is D.

4.

Force is given by:

F = dP/dt

dt = 0.05 sec

F = 75/0.05 = 1500 N

Correct option is B.

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