1. How does the back wheel of a bicycle turn if the torque of the chain/gear is applied at the center of the wheel?
2. In a real bicycle, the normal force on the front wheel from the ground acts slightly away from the vertical line passing through its centre. The average normal force on the front wheel acts
A. ahead of this line.
B. behind this line.
3. A free wheel is rolling without slipping on a rough horizontal surface. The magnitude and direction of the frictional force on the wheel are
A. non-zero, backward.
B. non-zero, forward.
C. zero, undefined.
4. Why does the bicycle stops if pedaling is stopped?
1. The back wheel of a bicycle turns when the torque from the chain/gear is applied at the center of the wheel due to the principle of conservation of angular momentum.
When the torque is applied to the center of the wheel, it creates a rotational force that tends to rotate the wheel. This rotational force causes the bike wheel to start rotating, resulting in the bike moving forward.
To understand this better, you can think of the bike wheel as a rotating object with angular momentum. When torque is applied to the wheel, it increases or decreases the angular momentum, causing the wheel to start rotating or change its rotation speed. This rotational motion eventually transfers to the bike, propelling it forward.
2. In a real bicycle, the normal force on the front wheel from the ground usually acts slightly behind the vertical line passing through its center.
This happens due to the weight distribution and the geometry of the bicycle. When a rider is sitting on the bicycle, their weight is distributed between the front and rear wheels. The weight distribution and the forward momentum of the bicycle cause a slight imbalance, resulting in a slightly greater normal force behind the vertical line passing through the center of the front wheel.
3. A free wheel rolling without slipping on a rough horizontal surface experiences a non-zero and backward frictional force.
When the wheel rolls without slipping, there is a relative motion between the surface and the wheel's point of contact. This relative motion creates a frictional force that opposes the direction of motion. In this case, the frictional force acts backward to prevent the wheel from sliding forward.
4. When pedaling on a bicycle is stopped, the bicycle eventually stops because there is no longer any external force propelling it forward.
When you pedal a bicycle, you apply a force to the pedals, which is transmitted through the chain and gears to the back wheel. This force creates a torque that rotates the back wheel, propelling the bicycle forward. As long as this force is applied, the bicycle maintains its forward motion.
However, when you stop pedaling, there is no longer any force being applied to the back wheel. Without this force, the rotational motion of the wheel gradually slows down due to friction and air resistance. Eventually, the bicycle comes to a stop since there is no external force to maintain its forward motion.