6.6.2 Torque and Angular Momentum Flashcards
The derivative of the equation L = r x p is
dL/dt = (dr/dt) x p + r x (dp/dt)
Which of the following states why the term dr/dt x p always vanishes?
dr/dt and p are always in the same direction
For a system of many particles, which of the following contributes to the net torque?
external torques only
For a bicycle wheel that experiences zero external torque, which of the following is true?
the angular acceleration is always zero
Which of the following equations is not a rotational analog to Newton’s second law?
t = r x F
The statement dL/dt = rx F is not true for
this equation is always true
Two objects are pulling each other with an action-reaction force as shown in the diagram. With respect to the origin shown, what is the torque action in object A compared to the torque acting on object B
tA = tB
Consider a rotating bicycle wheel and the torque due tot he friction acting on it. Which of the following effects is not due to this torque?
the term dL/dt will be greater than zero
An object is constrained to rotate in the xy-plane around a rigid massless rod, as shown in the diagram. In which of the following directions should a torque be applied in order to increase the angular momentum?
along the positive z-axis
If the external torque acting on a bicycle wheel is zero, which of the following statements is always true?
The angular momentum of the wheel is constant
