# Q5.11 In a world without friction, which of the following activi- ties could you do (or not do)? Explain your reasoning. (a) Drive around an unbanked highway curve; (b) jump into the air; (c) start walking on a horizontal sidewalk; (d) climb a vertical ladder; (e) change lanes while you drive.

Aakash
To Explain:The activities that could be performed without friction: (a) Drive around an unbanked highway curve; (b) jump into the air; (c) start walking on a horizontal sidewalk; (d) climb a vertical ladder;(e) Change lanes while you drive.Answer:Actions (a), (c), (e) cannot be performed but options (b) and (d) can be performed without friction.Explanation:Driving around the unbanked highway needs a horizontal centripetal force which is due to friction. If friction is not present there would be no centripetal force and driving around the unbanked highway would not be possible.To start walking on a horizontal sidewalk or to change lanes in a level road, the horizontal force required is provided by friction so if friction is not present it would not be possible.Jumping straight up the air or climbing a vertical ladder is managed by the force of gravity due to mass of the objects so these can be performed carefully without the presence of friction.
To Explain:
The activities that could be performed without friction: (a) Drive around an unbanked
highway curve; (b) jump into the air; (c) start walking on a horizontal sidewalk; (d) climb
a vertical ladder;(e) Change lanes while you drive.
Actions (a), (c), (e) cannot be performed but options (b) and (d) can be performed
without friction.
Explanation:
Driving around the unbanked highway needs a horizontal centripetal force which is due
to friction. If friction is not present there would be no centripetal force and driving around
the unbanked highway would not be possible.
To start walking on a horizontal sidewalk or to change lanes in a level road, the
horizontal force required is provided by friction so if friction is not present it would not
be possible.
Jumping straight up the air or climbing a vertical ladder is managed by the force of
gravity due to mass of the objects so these can be performed carefully without the
presence of friction.

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