Does the force of friction also act on the objects moving in the air

© Halfpoint/Fotolia Friction is a Depending on the circumstances, friction can be helpful or unhelpful. Friction between the sidewalk and the rubber soles of people’s shoes provides the traction needed to walk without slipping. Similarly, friction between brakes and the wheels of a car or bicycle helps the vehicles slow down. However, friction between the chain and axle of a bike makes it hard to pedal; to reduce friction, cyclists use oil or another lubricant on the chain so that it moves more freely. Friction between surfaces generates Forms of Friction There are two main types of frictional forces—static friction and kinetic friction. Static friction acts between surfaces that are in contact and at rest with respect to each other. It is the force that makes it difficult to start moving an object. The force of static friction must be overcome in order to move an object. That is, the magnitude, or size, of the applied force—the force applied to move the object—must be greater than the magnitude of the force of static friction. Once the force of static friction is overcome and an object is in motion, kinetic friction acts to oppose its movement. Kinetic friction acts between surfaces that are in motion relative to each other. To keep the object moving, force must be applied continuously; otherwise, kinetic friction will stop its movement. Factors That Influence Friction The amount of friction between two surfaces depends on the characteristics of the surfaces themselves. F...

Newton's First Law According to Newton's First Law of motion, an object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero, this means: • a stationary object stays stationary • a moving object continues to move at the same velocity (at the same speed and in the same direction) Inertia - Higher The tendency of an object to continue in its current state (at rest or in uniform motion) is called inertia . Examples of objects with uniform motion Newton's First Law can be used to explain the movement of objects travelling with uniform motion (constant velocity). For example, when a car travels at a constant speed, the driving force from the engine is balanced by resistive forces such as air resistance and friction in the car's moving parts. The resultant force on the car is zero. Other examples include: • a runner at their top speed experiences the same air resistance as their thrust • an object falling at terminal velocity experiences the same air resistance as its weight If the forces acting on an object are balanced, the resultant force is zero Examples of objects with non-uniform motion Newton's First Law can also be used to explain the movement of objects travelling with non-uniform motion. This includes situations when the speed, the direction, or both change. For example, when a car accelerates, the driving force from the engine is greater than the resistive forces. The resultant force is not zero. Other ex...

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© Halfpoint/Fotolia Friction is a Depending on the circumstances, friction can be helpful or unhelpful. Friction between the sidewalk and the rubber soles of people’s shoes provides the traction needed to walk without slipping. Similarly, friction between brakes and the wheels of a car or bicycle helps the vehicles slow down. However, friction between the chain and axle of a bike makes it hard to pedal; to reduce friction, cyclists use oil or another lubricant on the chain so that it moves more freely. Friction between surfaces generates Forms of Friction There are two main types of frictional forces—static friction and kinetic friction. Static friction acts between surfaces that are in contact and at rest with respect to each other. It is the force that makes it difficult to start moving an object. The force of static friction must be overcome in order to move an object. That is, the magnitude, or size, of the applied force—the force applied to move the object—must be greater than the magnitude of the force of static friction. Once the force of static friction is overcome and an object is in motion, kinetic friction acts to oppose its movement. Kinetic friction acts between surfaces that are in motion relative to each other. To keep the object moving, force must be applied continuously; otherwise, kinetic friction will stop its movement. Factors That Influence Friction The amount of friction between two surfaces depends on the characteristics of the surfaces themselves. F...

Physics and Natural Law Two simple experimental facts characterize the friction of sliding solids. First, the amount of friction is nearly independent of the area of contact. If a brick is pulled along a table, the frictional force is the same whether the brick is lying flat or standing on end. Second, friction is proportional to the load or weight that presses the surfaces together. If a pile of three bricks is pulled along a table, the friction is three times greater than if one brick is pulled. Thus, the ratio of friction F to load L is constant. This constant ratio is called the μ). Mathematically, μ = F/ L. Because both friction and load are measured in units of force (such as

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Newton's First Law According to Newton's First Law of motion, an object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero, this means: • a stationary object stays stationary • a moving object continues to move at the same velocity (at the same speed and in the same direction) Inertia - Higher The tendency of an object to continue in its current state (at rest or in uniform motion) is called inertia . Examples of objects with uniform motion Newton's First Law can be used to explain the movement of objects travelling with uniform motion (constant velocity). For example, when a car travels at a constant speed, the driving force from the engine is balanced by resistive forces such as air resistance and friction in the car's moving parts. The resultant force on the car is zero. Other examples include: • a runner at their top speed experiences the same air resistance as their thrust • an object falling at terminal velocity experiences the same air resistance as its weight If the forces acting on an object are balanced, the resultant force is zero Examples of objects with non-uniform motion Newton's First Law can also be used to explain the movement of objects travelling with non-uniform motion. This includes situations when the speed, the direction, or both change. For example, when a car accelerates, the driving force from the engine is greater than the resistive forces. The resultant force is not zero. Other ex...