1. During the trip you put a DVD on the player and snooze off in the back seat.
ID: 1412391 • Letter: 1
Question
1. During the trip you put a DVD on the player and snooze off in the back seat. You jerk awake and notice a book on the floor which is sliding over to the right. You surmise that the car is
A. Turning right and the acceleration is to the right
B. Turning left and the acceleration is to the left
C. Turning right and the acceleration is to the left
D. Turning left and the acceleration is to the right.
2. You arrive in New Orleans and immediately rent a bike so you can get around town without begging people for rides. Several of your other friends do this as well so you decide to go on a bike ride around the city center. Before starting you decide to play a game where everyone attempts to balance their bicycles while at rest. The person who can balance their bicycle the longest will win a free night out in the french quarter at a Jazz club. You find it extremely difficult to balance the bike. You constantly have to shift your weight left and right attempting to keep the bicycle balanced on the two wheels. In shifting your weight left and right you are:
keeping the back and forth movement of the bike centered over the two wheels.
keeping the average momentum of your center of mass close to zero.
keeping the net force on you and the bicycle averaging around zero.
keeping the center of mass exactly over the line connecting the two points where the wheels make contact with the road.
3. You lose the contest, and the group starts biking. It is a beautiful (but hot!) day, and so you ride your bicycle with no hands on the handle bars. As you go around a gentle turn to the left you are able to stear without touching the handle bars by leaning to the left so that the front wheel turns to the left. This happens because
the force of the pavement supporting the front wheel provides a torque which rotates the wheel.
leaning left automatically steers the bike to the left.
leaning left rotates the front wheel to the left, but there is no torque.
static friction against the front wheel rotates the wheel left.
A.keeping the back and forth movement of the bike centered over the two wheels.
B.keeping the average momentum of your center of mass close to zero.
C.keeping the net force on you and the bicycle averaging around zero.
D.keeping the center of mass exactly over the line connecting the two points where the wheels make contact with the road.
Explanation / Answer
Here,
1) as the book is sliding to the right
the car must be accelerating to the left
hence , the correct option is
B. Turning left and the acceleration is to the left
2)
AS for the bike to remain at rest , the center of mass must lie in the plane of contact of bicycle
hence ,
D. keeping the center of mass exactly over the line connecting the two points where the wheels make contact with the road.
3)
as there is frictional force between the wheel and the floor
D.
static friction against the front wheel rotates the wheel left.
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