Inertia

What Does Inertia Mean?

Inertia means resistance to action or change. It is a disapproving term used to show an inactive nature or sluggishness in a system. It is used in physics to describe the tendency of the body to remain lying down in a straight line without movement.

What Is the Relationship between Mass and Inertia?

The greater the mass the greater the inertia and the lower the mass the lower the inertia. The results are reversible such that the lower the inertia the lower the mass and the higher the inertia the higher the mass.

Reference:

www.physicsclassroom.com

Mass Inertia Relationship

·         Objects with more mass have more inertia. Thus, a very large boulder will be more difficult to move than a very small pebble. Similarly, once the large boulder starts moving, it will be more difficult to stop than the small pebble.

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xamples of Inertia

Inertia was best explained by Sir Isaac Newton in his first law of motion. Basically, the law of motion is that an object at rest stays at rest and an object continues in motion until an external force acts on it.

Taking a Look at Inertia Examples

• One's body movement to the side when a car makes a sharp turn.
• Tightening of seat belts in a car when it stops quickly.
• A ball rolling down a hill will continue to roll unless friction or another force stops it.
• Men in space find it more difficult to stop moving because of a lack of gravity acting against them.
• If pulled quickly, a tablecloth can be removed from underneath of dishes. The dishes have the tendency to remain still as long as the friction from the movement of the tablecloth is not too great.
• Shaking a bottle of ketchup. When bringing the bottom down, the suddenly stopping it, inertia is what causes the ketchup to come out of the bottle.
• When playing football, a player is tackled and his head hits the ground. The impact stops his skull, but his brain continues to move and hit the inside of his skull. His brain is showing inertia.
• If one drove a car directly into a brick wall, the car would stop because of the force exerted upon it by the wall. However, the driver requires a force to stop his body from moving, such as a seatbelt, otherwise inertia will cause his body to continue moving at the original speed until his body is acted upon by some force.
• Hovercraft are vehicles that can be a challenge to manipulate because, unlike cars, they do not have the same level of friction, so inertia causes the Hovercraft to want to continue in its same direction without stopping or turning.
• Abruptly stopping a cart with an object on top causes the object on top to fall off. Inertia causes this by making the object want to continue moving in the direction that it was.
• If a stopped car is hit by a moving car from behind, the passengers inside may experience whiplash as a result of the body moving forward but the head lagging behind. The head is experiencing inertia.
• If a car is moving forward it will continue to move forward unless friction or the brakes interfere with its movement.
• When a baseball is thrown it will continue to move forward until acted upon by gravity. The greater the force of the throw, the harder it is for gravity to act upon it.
• A hockey puck will continue to slide across ice until acted upon by an outside force.
• A balloon in a car will appear to move when the car moves forward, but the balloon is actually attempting to stay in the place it was, it is only the car that is moving.
• When a car is abruptly accelerated, drivers and passengers may feel as though their bodies are moving backward. In reality, inertia is making the body want to stay in place as the car moves forward.
• If an index card is placed on top of a glass with a penny on top of it, the index card can be quickly removed while the penny falls straight into the glass, as the penny is demonstrating inertia.
• If you jump from a car of bus that is moving, your body is still moving in the direction of the vehicle. When your feet hit the ground, the grounds act on your feet and they stop moving. You will fall because the upper part of your body didn’t stop and you will fall in the direction you were moving.
• When you stir coffee or tea and stop, the swirling motion continues due to inertia.
• Objects that establish orbit around the earth, like satellites, continue on their trajectory due to inertia.
• Inertia of rest is an object staying where it is placed and it will stay there until you or something else moves it.
• If you throw a rock straight up, it will not vary from its direction. This is an example of inertia of direction.
• Inertia enables ice skaters to glide on the ice in a straight line.
• If the wind is blowing, a tree’s branches are moving. A piece of ripe fruit that falls from the tree will fall in the direction the wind is moving because of inertia.
• When peddling a bicycle, if you stop pedaling, the bike continues going until friction or gravity slows it down.
• When pulling a Band-Aid off, it is better to pull it fast. Your skin will remain at rest due to inertia and the force pulls the Band-Aid off.
• A car that is moving will continue even if you switch the engine off.
• If a ball is on a slanted surface and you let go, gravity will make it roll down the slope. It has inertia and if there is a level area at the bottom of the slope, it will continue moving.
• When entering a building through a rotating door, inertia will allow the door to hit you in the back if you don’t get out of the way.
• If you are rolling a cart with something on top and you hit something that makes the cart stop, what is on top may fall off.
• It is harder to stop a big vehicle, like a bus, than a smaller vehicle, like a motorcycle. There is more inertia with the bigger object.
• A concussion occurs because your brain is still moving while the outside skull is stopped. This is what causes the injury.
• Space probes are launched to get past the Earth’s atmosphere. Then they coast due to inertia.
• If you are on a train and the train is moving at a constant speed, a toy tossed into the air will go straight up and then come down. This is because the toy has inertia like the train and you. 

See if you can recognize inertia when it occurs over the course of your day.

We are subject to the concept of inertia and experience such an idea every single day. Here are some examples. 1. Suddenly accelerating during a car ride makes the driver and the riders feel pushed up against their seats. Inertia explains this phenomenon quite clearly. 2. Turning around a corner while driving makes the driver and the riders move quite counter-intuitively. For example, if a car turns right, every person in the car is pushed to left and vice versa; inertia explains this phenomenon. 3. We usually shake the bottle of ketchup or hit it in order to get that last bit of ketchup remaining in the bottle. We do both of these things to move the ketchup as the remaining bit of ketchup is subject to the idea of inertia when shaken or hit. 4. After sprinting for a while, you must apply a backward force in order to stop. Yet if you do not apply this backward force, you will continue moving forward. If you stop running suddenly, you will for a second move at the speed at which you were running before. Inertia helps to explain this phenomenon. 5. If a bus suddenly stops and you aren't holding onto a support, you will be pushed to the front of the bus. Your mass and the concept of inertia helps to explain such a phenomenon.

CAR

People encounter inertia on an everyday basis. For example, someone driving a car will experience a force pushing her back against the seat when the car is speeding up; this is due to the driver’s resistance to the car’s forward movement. Similarly, when the car slows down the driver is pushed forward — relative to the car — again, due to her resistance to the change in motion. This is why seat belts are an essential safety feature in cars. If the driver has to break suddenly, the occupants would continue moving forward at the original speed, and without seat belts to restrain them, they could be seriously injured.
The car’s own inertia is an important consideration for drivers. It explains why moving vehicles have a stopping distance that is dependent on the speed and the mass of the vehicle. A car’s resistance to a change in motion also explains why the car will skid out of control if the driver tries to turn too quickly: the vehicle will tend to continue moving in the same direction.

Momentum

Momentum is the quantity of  motion .Any thing in the universe is characterized by the quantity associated with it. In motion both mass and velocity contribute to its quantity. Momentum is the product of mass and velocity.

The unit of momentum is?

P (symbol for momentum) = mass * velocity

momentum units = mass units * velocity unies

momentum unites = kg * m/s

p = kgm/s

The Principle of the Conservation of Momentum states that: if objects collide, the total momentum before the collision is the same as the total momentum after the collision (provided that no external forces - for example, friction - act on the system).

That's amazingly useful because it means that you can tell what is going to happen after a collision before it has taken place.

FORCE

The Meaning of Force

• The Meaning of Force
• Types of Forces
• Drawing Free-Body Diagrams
• Determining the Net Force

A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. When the interaction ceases, the two objects no longer experience the force. Forces only exist as a result of an interaction.

WHAT IS TORQUE?

Torque is a measure of how much a force acting on an object causes that object to rotate. The object rotates about an axis, which we will call the pivot point, and will label 'O'. We will call the force 'F'. The distance from the pivot point to the point where the force acts is called the moment arm, and is denoted by 'r'. Note that this distance, 'r', is also a vector, and points from the axis of rotation to the point where the force acts. (Refer to Figure 1 for a pictoral representation of these definitions.)

Unbalanced Force

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Replies:

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Sharon,

An unbalance force is one that is not opposed by an equal and opposite force operating directly against the force intended to cause a change in the object's state of motion or rest. Consider this little illustration:

Object, O is at rest and subjected to a force from the left as shown:

Let ====> represent the force to change the object's state of motion or rest on object. O

This unopposed (unbalanced) force will cause the object to move to the right. ====> O

Let O <==== represent an opposing force of equal magnitude operating on object O.

When the forces are opposed and impinging on the object ====> O <====, the object will not move because each force is balanced by an equal and opposite force.

However, if the forces are unbalanced and aligned thus, ====> O <========, the larger force coming from the right is unbalance by the one from the left. Thus, the object will move toward the left.

The picture is more complicated that I can illustrate here because an opposing force my be impinging on the object from an angle. Overall, it is the "net" unbalanced force that will cause the object to move or change its state of motion.

What is the meaning of unbalanced force?

Unbalanced force occurs when two forces acting on an object are not equal in size, causing a change in motion. Unbalanced forces cause a still object to move or moving objects to slow down or speed up, stop or change direction.
A balanced force exists when opposing forces are of equal magnitude, ultimately canceling each other out and resulting in no motion. Unbalanced forces are not equal or opposite. When two unbalanced forces are exerted in opposite directions, the net force is equal to the difference between the two forces, resulting in motion in the direction of the larger force.

FORCE

The Effects of Forces

A force acting on an object may cause the object to change shape, to start moving, to stop moving, to accelerate or decelerate.

When two objects interact with each other they exert a force on each other, the forces are equal in size but opposite in direction.

Resultant force

The forces acting on an object can be replaced with a single force that causes the object to behave in the same way as all the separate forces acting together did, this one overall force is called the resultant force. All forces (F) are measured in newtons (N).

If the resultant force acting on an object is ZERO then;

• the object will remain stationary if it was stationary when the resultant force became zero
• move at a constant (steady) speed in a straight line  if it was moving when the resultant force became zero\

·         The relationship among mass force and acceleration is explained by what?

·        

·         Science Supervisor Ganderton

·         Newton's second law states that the net force on a body is equal to its mass multiplied by its acceleration, or in symbols: F = ma.Note that force and acceleration are vectors - they have both magnitude and direction.

Acceleration and Mass Relationship?

What is the relationship between mass and acceleration for cars?

Hey look,
Mass and acceleration are inversely proportional
Apply Newton's second law
F=ma
so if the net force is constant as the mass increase,the acceleration decrease and vice versa.....

Hope that helped you!

Source:

My phyics teacher

kendizzle answered 7 years ago

Newtons Second Law of Motion

force = mass * acceleration

this is the governing mass/acceleration relation for all objects on earth that have non-negligable masses.