Question

plz answer all four questions, thanks!

Questions 20-21 A wheel of mass m, which has a rotational inertia I and a radius r, rotates with an angular speed w about an axis through its center. A retarding force F is applied tangentially to the rim of the wheel. 22. An airplane travels horizontally at a constant velocity v. An object is dropped from the plane, and one second later another object is dropped from the plane. If air resistance is negligible, what happens to the vertical distance between the two objects while they are both falling? 20. Which of the following is equal to the magnitude of the angular acceleration of the wheel? (A) It increases. (B) It decreases. (C) It remains the same. (D) It depends on the mass of the objects. (E) It depends on the horizontal speed of the plane. 23. A boat moves across a river. The river's velocity relative to the land is VRL, and the boat's velocity relative to the river is VR . Which of the following best represents the velocity of the boat relative to the land? (A) VER + VRL (B) BR - ÜRL (C) - Br + URL (D) PBRl+lürel (E) PBR] - PRL! 21. The retarding force F finally stops the rotation of the wheel. Which of the following best represents the total reduction in mechanical energy in the process of stopping the wheel? (A) Fr (B) 1602 (C) or (D) Fr?

Answer 1

20. torque ..............(B)

T=rXF=la

21. We are stopping the wheels, means converting kinetic(motion related) energy to some other. .............(E)

22. As both of them are accelerating with same acceleration increase in velocity at given time interval is same for both. That's why the increase in distance will also be same. .(C)

23. Velocity is a vector. So, the relatives velocities have to added as vectors only. ........(A)