Physics H131: Problem Set #15

Chapter N9 Problems

• N9B.3: This is very similar to the car problem N9B.4 done in class. Assign frames S and S' so that you can use the velocities given and then use the Galilean transformation formula to read off the velocity of the plan in the frame of the air (or the other way around). Remember that the speed is the magnitude of the velocity.
• N9B.5: This is very similar to N9B.8, which we did in class. Use the acceleration transformation equation for part b) after identifying frames S and S'.
• N9B.6: Once again, assign S and S', figure out A and then apply the acceleration transformation formula. The answer should be intuitive.
• N9S.3: In this case the person has the same acceleration as the airplane in the ground reference frame, so calculate this first. Then apply Newton's law in that frame. Then transform to the plane frame. What is the person's acceleration in that frame? So what fictitious force is needed so that F=ma works in that frame?
• N9S.6: Similar to N9S.7 done in class. The question asks for revolutions per second, not angular velocity (so they want 1/T, not 2*pi/T).
• N9S.8: The detector is on the earth's equator, so it is moving in a circle with a radius equal to the earth's radius. The floating ball has the same initial velocity as the detector when it is released, but what path does it take when it is free? In the frame of the detector, what is the fictitious force on the ball? (Use this to answer the question in the problem!)
• N9R.1 You'll need to estimate the distance between floors. Remember that your "apparent" weight is equal to the normal force on you from the elevator or (since we are in chapter N9 :), your mass times the effective gravity. The latter lets you find the acceleration of the elevator with respect to the ground.

Chapter N10 Problems

• N10T.4: Use equation (N10.6). If we ignore air resistance and assume that the force of gravity is simply mg with the direction of g constant, what can we say about the acceleration?
• N10B.5: Draw a good picture, assign an origin and coordinate axes, then just apply equation (N10.7).
• N10B.7: You are given m and C. What is rho for this problem? How do you calculate A given the diameter of the ball?
• N10S.4: This is like N10S.6, which we did in class. Draw a good picture, assign an origin and coordinate axes, then just apply equation (N10.7), given the initial and final values stated in the problem.