1. How does friction affect forward motion? Give an example.
2. Describe two ways to change the frictional force between two solid surfaces.
- Change the lubrication between the two surfaces.
- Change the normal force between the two surfaces.
3. How does air resistance affect the velocity of a falling object?
4. What two sources of friction do you have to overcome when you are walking?
5. If you push a chair across the floor at a constant velocity, how does the force of friction compare with the force exerted? Explain.
6. If you push a book against a wall hard enough, it will not slide down even though gravity is pulling it. Use what you know about Newton’s laws of motion to explain why the book doesn’t fall.
Answer (3)
1. Friction affects forward motion by repelling or trying to cancel the force which the opposite of its direction. For example, the wheel against the road pavement.
Air resistance affect the velocity of a falling object by either interfering with the gravitation force the object is acting on the subject. Hence, these since air assuming that the direction is perpendicular with gravity will result the object to drop sideways or gradually.
The friction of the pavement and the air molecules.
Since the exerted force of the human is greater the object moves until the frictional force cancel itself or produce a net force both the force of the chair, gravity and friction.
Third law of motion which states that the force exerted of A to B, B will exert the same force that was exerted by A leaving the gravitational force canceled.
Friction and Motion
Friction affects forward motion by opposing the direction of movement. For example, when a car moves forward, friction between the tires and the road resists the car's motion, providing traction that enables the car to move ahead. To change the frictional force between two solid surfaces, you can alter the type of lubrication used, making the surfaces more or less slippery. Alternatively, increasing or decreasing the normal force - the force perpendicular to the surfaces in contact - will affect friction since frictional force is proportional to the normal force.
Air resistance affects the velocity of a falling object by opposing the pull of gravity, eventually causing the object to reach a terminal velocity where the force due to air resistance equals the force due to gravity, resulting in no acceleration. When you are walking, you have to overcome both static friction, which keeps you from slipping when you start to step, and kinetic friction, which acts against your foot as it moves backwards across the ground.
If you are pushing a chair across the floor at a constant velocity, the force of friction is exactly equal to the force you exert. This is due to Newton's first law of motion, which states that an object at constant velocity is experiencing no net force, implying that the opposing forces are balanced.
When you push a book against a wall, it does not slide down because the static frictional force is equal to the force of gravity pulling it down. This is in accordance with Newton's third law of motion, which asserts that for every action, there is an equal and opposite reaction. The static frictional force acting up the wall is the reaction force to the force you exert pushing the book against the wall.
Friction opposes motion by acting in the opposite direction to moving objects, while air resistance slows falling objects by counteracting gravity. Friction can be altered through lubrication or changes in normal force, and when walking, friction from the ground and air resistance are the main sources. A balance of forces allows a book to remain against a wall due to gravity and the opposing wall force acting on it.
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