An object with greater is more difficult to stop or start

Momentum is another vector measurement. Momentum is in the same direction as velocity. Scientists calculate momentum by multiplying the mass of the object by the velocity of the object. It is an indication of how hard it would be to stop the object. If you were running, you might have a mass of 50 kilograms and a velocity of 10 meters per second west (really fast). Your momentum would be 500 kg-m/sec west. Easy as pi.

Remember Newton's First Law? It said that any object moving will continue moving unless it is interfered with. That idea applies to momentum as well. The momentum of an object will never change if it is left alone. If the 'm' value and the 'v' value remain the same, the momentum value will be constant.

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Conserving Momentum
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The momentum of an object, or set of objects (system), remains the same if it is left alone. Within such a system, momentum is said to be conserved.

Here's the momentum idea in simpler terms. When you throw a ball at someone and it hits him hard, it hurts because it was difficult to stop (had momentum).Think about it. If you throw a small ball and a large ball at the same speeds, the large ball will hit a person with a greater momentum, be harder to stop, and hurt more. When the mass is greater (at the same speeds), the momentum is greater. A bullet is an example of an object with a very small mass that has a lot of momentum because it is moving very quickly. Bullets are therefore difficult to stop; it's a good idea not to try!

Conserving Momentum

We already told you that the momentum of an isolated object (or system of objects) is conserved. If the net force acting on an object is zero, then the linear momentum is constant. In an elastic collision (such as a superball hitting and rebounding from the ground), no kinetic energy is lost. All of that energy is still in the object, so we say that energy was conserved. If the kinetic energy didn't change, then neither did the value of the momentum (The momentum vector, however, DID change, since the direction of momentum changed.). Energy is a scalar, not a vector, so a direction change doesn't matter.

What about an inelastic collision? In an inelastic collision, some of the energy will be lost to heat or sound or light or some other energy. The thing to remember is that the total energy didn't change, but some of it escaped into the air, ground, etc. The object would then have less energy when it rebounded, so the KE and momentum would be less. The total energy is the same, but the energy of the object did not remain the same. The energy of the object was not conserved, but the total energy was.

Try throwing a piece of clay on the ground. When the clay slams into the ground, some of the kinetic energy of the clay was lost as heat and sound to the ground and air, and some of the heat remains in the clay. Since the velocity became zero, so did the momentum. The energy is still around, but divided up in different places.

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Hint: Mass of an object is directly proportional to the inertia possessed by it. We know that anything which has more mass is difficult to move from its rest. Because its inertia resists the motion of an object. Hence, it’s tough to move from its rest state.
Complete answer: More the mass is more difficult to move a loaded trolley rather than an unloaded one means to say is greater the mass more difficult to stop or move the body.Example:One bucket is filled with sand and the other is empty and initially, both buckets are at the state of rest. These buckets are pushed into a swinging motion when the bucket with sand would require more force because it has more mass or inertia.Because a bucket filled with sand has a bigger mass compared to an empty bucket. The mass of the object which resists change in motion is directly proportional to the inertia. The Inertia will be increased when the mass is increased, and you need greater force to move or stop the heavier mass object.Therefore, a body is difficult to move from rest because of having more mass i.e. because of inertia.

Note: The filled bucket has more inertia than the empty bucket because heavier or more massive objects offer larger inertia.

Inertia is a natural tendency of an object to resist a change in its state of motion and inertia is actually measured based upon the mass of an object.The mass is solely dependent upon the inertia of an object. Similarly, the more inertia an object has the more mass.

Generally describe what a force is and name some common forces.
Describe gravitational force and how this force pulls objects towards the surface of the earth at the same rate, regardless of mass.
Describe a scenario that demonstrates the property of inertia.
Understand the concept of action and reaction forces.
Compare the effect of friction on the movement of an object over a variety of surfaces.

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Background

The basis of classical mechanics (the study of “how stuff moves”) is Newton’s Three Laws of Motion, which can be used to explain the movement of everything from prodigious planets to petite blood platelets.

First Law: The Law of Inertia
Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by external forces.

That is, without a force (a push or a pull) intervening, objects tend to keep moving if they’re moving or tend to stay stopped if they’re stopped. Examples of this are astronauts in space, who keep on moving in a straight line until they bump into something, or a ball that won’t move on its own until you kick or push it.

Second Law: Force = mass x acceleration
Force is equal to the change in momentum per change in time. In other words, for a constant mass, the force acting on it equals its mass times its acceleration due to gravity.

Things with more mass (heavier things) require more force to speed up as quickly as things with less mass (lighter things). Imagine trying to throw an orange and a watermelon. The bigger the force, the greater the acceleration (the change in an object’s velocity). It’s also harder to stop a heavier object than it is to stop a lighter one.

Third Law
For every action there is an equal and opposite reaction.

If you push on something, it will push right back. For example, your feet have to push back on the ground in order for you to walk forward. The explosive combustion inside a rocket throws exhaust out its bottom, while propelling the rocket upwards with equal force.

Vocabulary

force: A push or a pull action on an object.
inertia: The tendency for objects in motion to stay in motion, and objects at rest to stay at rest, unless acted upon by an outside force.
friction: The resistance an object meets when moving over a surface or through a gas or liquid; it is the force that resists the motion of two surfaces that are touching each other.
mass: The amount of matter in an object, which is measured in grams (g) or kilograms (kg).
acceleration: A change in an object’s velocity (speed) over time (from not moving to moving, or from moving quickly to moving slowly or stopping).
velocity: How far an object travels in a certain direction over a period of time.
gravity: The force of attraction which the earth exerts on objects on or near its surface, pulling them downwards. It is also the force of attraction between any two objects.

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How Stuff Works| Newton’s Laws of Motion

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LAWS OF MOTIONINERTIAMOMENTUMFIND OUT MORE

Dynamics is the study of how objects move when forces act on them. Normally objects stay still or move along at a steady pace. They resist changes in their motion because of their INERTIA. Once they start moving, they tend to carry on doing so because of their MOMENTUM. Most types of everyday movement can be explained by just three simple LAWS OF MOTION. These were originally worked out by English physicist Sir Isaac Newton.

Newton’s three laws of motion (often called Newton’s laws) explain how forces make objects move. When the forces that are acting on an object are balanced, there is no change in the way it moves. When the forces are unbalanced, there is an overall force in one direction. This changes the object’s speed or the direction in which it is moving. Physicists call a change in speed or direction an acceleration.

An object will stay still or move along at a steady pace unless a force acts on it. For example, a rocket on a launchpad remains in place because there is no force acting on it to make it move.

When a force acts on an object, it makes the object change speed or move in a different direction. When the rocket’s engines fire, the force they produce lifts the rocket up off the launchpad and into the air.

When a force acts on an object, the object pulls or pushes back. This reaction is equal to the original force but in the opposite direction. As the hot gases shoot down from the engines, an equal force pushes the rocket up.

Newton’s three laws of motion enabled him to produce a complete theory of gravity, the force that dominates our Universe, and to explain why the Moon circles round Earth. Newton also made major discoveries about optics (the theory of light) and explained how white light is composed of many colours.

Newton’s first law explains that objects remain where they are or move along at a steady speed unless a force acts on them. This idea is known as inertia. The greater the weight (or mass) of an object, the more inertia it has. Heavy objects are harder to move than light ones because they have more inertia. Inertia also makes it harder to stop heavy things once they are moving.

As a car accelerates, passengers are thrown backwards; when a car brakes or crashes, passengers are thrown forwards. In both cases, this is because the inertia caused by their mass resists the change in movement. During crash-tests, dummies that weigh the same as a human body are used to help test safety belts and airbags.

Moving objects carry on moving because they have momentum. The momentum of a moving object increases with its mass and its speed. The heavier the object and the faster it is moving, the greater its momentum and the harder it is to stop. If a truck and a car are travelling at the same speed, it takes more force to stop the truck because its greater mass gives it more momentum.

A foal is smaller and has less mass than a horse. When a foal and a horse gallop along together at the same speed, the horse has more momentum because of its greater mass. This means that it is easier for the foal to start moving, stop moving, and change direction than the horse. The momentum of a moving object is equal to its mass times its velocity.

Energy

Forces

Gravity

Motion

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