- #1
zhenyazh
- 56
- 0
hi,
could some on help me understand why the following is true?
for some of them i wrote exactly what i don't understand, for others
i really have no idea
Two uniform rods are connected to a table by pivots at one end. Rod B is longer than rod A. Both are released simultaneously from an initial angle θ. Neglect air friction. NOTATION: CM = center of mass; α = angular acceleration; |ay|= size of downward acceleration.
True: αA and αB are dependent on θ.
just don't understand why.
False: |ax| of the CM initially equals 0 for both rods.
this would be false because of the centr. force right?
True: |ay| is initially equal for the CM of A and B.
that is because it is g right?
True: Just before landing, the CM of B has a greater speed than the CM of A.
why so? i found an explanation on the internet but there they comapered mgh to 0.5Iw^2
and from there proved b's speed is larger therefore the answer.
but why can i use such an equation? why do i not take into consideration the kinetic energy
of center of mass and how do i define the height here? according to the center of mass?
False: Rods A and B hit the table at the same time.
False: αA and αB are the same initially.
True: αA and αB both increase with time.
thanks
could some on help me understand why the following is true?
for some of them i wrote exactly what i don't understand, for others
i really have no idea
Two uniform rods are connected to a table by pivots at one end. Rod B is longer than rod A. Both are released simultaneously from an initial angle θ. Neglect air friction. NOTATION: CM = center of mass; α = angular acceleration; |ay|= size of downward acceleration.
True: αA and αB are dependent on θ.
just don't understand why.
False: |ax| of the CM initially equals 0 for both rods.
this would be false because of the centr. force right?
True: |ay| is initially equal for the CM of A and B.
that is because it is g right?
True: Just before landing, the CM of B has a greater speed than the CM of A.
why so? i found an explanation on the internet but there they comapered mgh to 0.5Iw^2
and from there proved b's speed is larger therefore the answer.
but why can i use such an equation? why do i not take into consideration the kinetic energy
of center of mass and how do i define the height here? according to the center of mass?
False: Rods A and B hit the table at the same time.
False: αA and αB are the same initially.
True: αA and αB both increase with time.
thanks