- #1
Bonulo
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I've been presented with the following problems:
SITUATION:
A ball is rolling without slipping with velocity [itex] v [/itex] on a horizontal surface. It reaches an incline, which forms an angle [itex] \theta [/itex] with the horizontal. In which situation will the ball reach the highest point, when the incline has a rough surface, so the ball does natural roll or when the surface is completely smooth?
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Obviously, the difference is the lack of friction in the latter situation. The friction [itex] f_r [/itex] in the first situation makes the ball's rotational velocity drop, and the tangential component of the ball's weight [itex] w [/itex], [itex] m g sin(\theta) [/itex] in both situations slows down the ball's translational velocity.
I'm not sure whether the ball on the smooth surface will continue rolling (naturally), since there's no torque applied, since it was rolling naturally immediately before it met the incline.PROBLEM a)
Explain your answer with regards to conservation of energy.
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The equation is [itex] U_1 + K_1 + W_[other] = U_2 + K_2 [/itex], and I can make it [itex] K_1 + W_[other] = U_2 [/itex]. But does the rolling friction do any work (when the ball rolls on the rough surface)? And how can the question of which ball reaches the biggest height be answered - by elmininating the rotational kinetic energy for the ball on the smooth surface, or by the work, if there is any?
PROBLEM b)
Explain your answer with regards to Newton's laws.
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I guess I have to use Newton's 2nd law here, and show that the existence of friction on the rough surface gives the ball linear acceleration up the incline, while slowing its rotation down.
Am I right? And if I'm not; am I far from the truth? :shy:
SITUATION:
A ball is rolling without slipping with velocity [itex] v [/itex] on a horizontal surface. It reaches an incline, which forms an angle [itex] \theta [/itex] with the horizontal. In which situation will the ball reach the highest point, when the incline has a rough surface, so the ball does natural roll or when the surface is completely smooth?
-----
Obviously, the difference is the lack of friction in the latter situation. The friction [itex] f_r [/itex] in the first situation makes the ball's rotational velocity drop, and the tangential component of the ball's weight [itex] w [/itex], [itex] m g sin(\theta) [/itex] in both situations slows down the ball's translational velocity.
I'm not sure whether the ball on the smooth surface will continue rolling (naturally), since there's no torque applied, since it was rolling naturally immediately before it met the incline.PROBLEM a)
Explain your answer with regards to conservation of energy.
-----
The equation is [itex] U_1 + K_1 + W_[other] = U_2 + K_2 [/itex], and I can make it [itex] K_1 + W_[other] = U_2 [/itex]. But does the rolling friction do any work (when the ball rolls on the rough surface)? And how can the question of which ball reaches the biggest height be answered - by elmininating the rotational kinetic energy for the ball on the smooth surface, or by the work, if there is any?
PROBLEM b)
Explain your answer with regards to Newton's laws.
-----
I guess I have to use Newton's 2nd law here, and show that the existence of friction on the rough surface gives the ball linear acceleration up the incline, while slowing its rotation down.
Am I right? And if I'm not; am I far from the truth? :shy:
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