Friction

Inertia is the resistance of any physical object to any change in its velocity. This includes changes to the object’s speed, or direction of motion. Thus, an object will continue moving at its current velocity until some force causes its speed or direction to change.

Friction: A force that opposes the motion of objects that touch as they move past each other. Friction acts at the surface where objects are in contact. Terminal Velocity: The constant velocity of a falling object when the force of air resistance equals the force of gravity.

Friction, force that resists the sliding or rolling of one solid object over another.

Answer. Answer: Inertia is a force which keeps stationary objects at rest and moving objects in motion at constant velocity. Inertia is a force which brings all objects to a rest position.

KEY CONCEPT. Friction is a force that. opposes motion.

FRICTION: Friction is a force that opposes motion. When two objects are in contact, friction is acts in a direction opposite to the motion of the object.

Friction – a force that opposes motion between two surfaces that are touching. Gravity – a pull that attracts objects to each other. This is a force. Balanced forces – equal in strength but opposite in direction.

Friction is a force that occurs when two surfaces slide past one another. The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down. When objects move through a fluid, such as air or water, the fluid exerts a frictional force on the moving object.

*Motion, Forces, & Energy – Ch. 2 “Forces” Games

Normal force is defined as the force that a surface exerts on an object. This is also in accordance with Newton’s third law, which suggests that the normal force will be equal and opposite the force of weight.

When an object is placed on an inclined plane, its weight vector can be resolved into the normal force, which is equal to the force of the object perpendicular to the plane, and a parallel force, which pushes the object down the inclined plane.

If a body is moving with constant velocity, acceleration is zero. So net force acting on it will be also zero.

For example, when a book is placed on a table, the normal force keeps the book from falling through the table. Gravity is pulling the book downward, but since the book isn’t actually falling, something must be pushing it up. This force is called the normal force.

In pushing,component of force adds up to the body and due to this normal reaction from ground increases resulting in increase in friction. Hence pushing becomes harder compared with pulling. In pulling normal reaction from ground decreases so friction also will be decreased. Therefore pulling is easier than pushing.

The results suggest that for our group of healthy recreationally active subjects, the upper body “pushing” musculature is approximately 1.5–2.7 times stronger than the musculature involved for pulling.

If two forces act on an object in the same direction, the net force is equal to the sum of the two forces. This always results in a stronger force than either of the individual forces alone.

A non-contact force is a force which acts on an object without coming physically in contact with it. The most familiar non-contact force is gravity, which confers weight. All four known fundamental interactions are non-contact forces: Gravity, the force of attraction that exists among all bodies that have mass.

But in the atmosphere, the motion of a falling object is opposed by the air resistance, or drag. The drag equation tells us that drag (D) is equal to a drag coefficient (Cd) times one half the air density (r) times the velocity (V) squared times a reference area (A) on which the drag coefficient is based.

If you know the total current and the voltage across the whole circuit, you can find the total resistance using Ohm’s Law: R = V / I. For example, a parallel circuit has a voltage of 9 volts and total current of 3 amps. The total resistance RT = 9 volts / 3 amps = 3 Ω.

The force due to air resistance is proportional to the speed, and is applied in the direction opposite to motion. The faster the object moves, the more collisions and so the greater the overall force due to air resistance.

Since acceleration is a change in velocity, we can in fact have velocity without acceleration. Essentially, it takes more air resistance to cancel out the object’s weight, and that resistance increases as the object’s velocity increases. Terminal velocity can also be adjusted by surface area.

heavy objects will have a higher terminal velocity than light objects. It takes a larger air resistance force to equal the weight of a heavier object. A larger air resistance force requires more speed.) Therefore, heavy objects will fall faster in air than light objects.

Greater speed causes greater air resistance, and increased area increases air resistance as well. It also depends on an object’s shape. When a plane drops from a high altitude to a lower one, it naturally speeds up just like anything that is dropped.

If there is no air resistance, after you let go of an object the only force on it is the gravitational force. More massive objects have a greater gravitational force. The acceleration of an object is proportional to the net force on the object and inversely proportional to the mass of the object.

Two ways to reduce air resistance are stated: reducing the area in contact with air (by the cyclist ducking down or cycling behind someone else) and by being more streamlined (wearing smoother surfaces or a more streamlined helmet).

You might think this is because the air resistance force depends on the mass, but you’d be wrong– it’s exactly the opposite. Air resistance is insignificant for heavy objects precisely because it doesn’t depend on the mass. Specifically, the change in motion due to air resistance gets bigger as the mass gets smaller.