Relationship between mass and inertia.

1. A shopper in a supermarket observes that it is always easier to start moving an empty grocery cart than a full cart.
2. Similarity, it is easier to stop an empty cart than a full one if both are moving at the same speed towards the shopper.
3. Thus, the resistance to change to velocity (including zero velocity) i.e. the inertia is related to the mass of the object. Since the mass for the full cart is more than the empty one, and the full cart offers more inertia, it is obvious that inertia increases when mass increases.
4. By the same reasoning, a bowling ball is harder to stop than a hollow rubber ball of the same size.
5. However, inertia is a phenomenon. It has no unit even it is closely related to mass, which has a SI unit of kilogram.

Conclusionly, inertia of an object is the object's resistance to change in its motion or its state of rest. If mass increase, then inertia will increase.Magnitude of inertia (mass) can be shown by an inertia balance.

• Concept of inertia....
• All objects tend to continue what they are doing.
• An object at real tends to remain at rest, while an object in motion tends to stay in motion in a straight line with the same speed unless being acted upon by an unbalanced force.
• Only an external force (on non-zero net force) can cause a change to the state of motion of an object (either at rest or moving with the same speed in a straight line).
• However, the object will resist any attempt to do so.The Tedency of an object to resist changes to its state of motion is described as inertia. Everything has inertia , making it reluctant to move or to stop.
• Newton's first law of motion (also known as the Law of Inertia)states that:

An object at rest tends to stay at rest and a moving object tends to continue its uniform motion with the same speed and in the same direction unless being acted upon by an external force.

• The external force is a non-zero net force, if more than one external force acts on the object.

Summary of the equation for linear motion with uniform acceleration

1) v=U+at
2) s=1/2 (u+v)t
3) s=ut+1/2(at)2
4) (v)2=(u)2+2as

by Nanthini

Physics Form 4: Chapter 2 - Forces in Equilibrium

Physics Form 4: Chapter 2 - Forces in Equilibrium

• If an object is at equilibrium, then the forces are balanced which means that resultant force is zero. According to F = ma, the object's acceleration also zero when force in equilibrium achieved.

An object at equilibrium is either ...

• at rest and staying at rest, or
• in motion and continuing in motion with the same speed and direction.

  

Object at equilibrium position. The load is static.

Force A = 3.4 N  at an angle of 161 degree

Force B = 9.2 N at an angle of 70 degree

Force C = 9.8 N at an angle of 270 degree

A triangle of forces diagram showing forces are in equilibrium

Source: http://cikguwong.blogspot.com/2011/05/physics-form-4-chapter-2-forces-in.html