physics year 9

What is the principle of moments?

• The principle of moments indicates that an object will always rotate in a clockwise direction.

• The principle of moments is about the conservation of energy in a closed system.

• The principle of moments is that the sum of clockwise moments equals the sum of counterclockwise moments for an object in equilibrium.

• The principle of moments states that all forces acting on an object must be equal.

Define a lever and its types.

• A lever is a type of pulley used for lifting heavy objects.

• A lever is a tool used exclusively in construction and has no types.

• A lever is a complex machine with two types: static and dynamic.

• A lever is a simple machine with three types: first-class, second-class, and third-class.

How does a first-class lever work?

• A first-class lever uses a pulley to lift heavy objects.

• A first-class lever requires no effort to move the load.

• A first-class lever operates without a fulcrum.

• A first-class lever works by using a fulcrum to balance effort and load, allowing movement with less force.

What is the formula for calculating moments?

• M = F + d

• M = F / d

• M = F - d

• M = F × d

Explain the difference between static and dynamic equilibrium.

• Static equilibrium is when forces are unbalanced; dynamic equilibrium is when forces are balanced but changing.

• Static equilibrium is when an object is at rest with balanced forces; dynamic equilibrium is when an object is in motion at constant velocity with balanced forces.

• Static equilibrium occurs only in liquids; dynamic equilibrium applies only to gases.

• Static equilibrium involves an object moving at high speed; dynamic equilibrium is when an object is stationary.

What is the role of the fulcrum in a lever?

• The fulcrum is the force applied to the lever.

• The fulcrum is the load being lifted by the lever.

• The fulcrum is the length of the lever arm.

• The fulcrum acts as the pivot point in a lever.

Describe how electrostatic forces are generated.

• Electrostatic forces are generated by the movement of magnetic fields.

• Electrostatic forces are created by the flow of electric current in a circuit.

• Electrostatic forces arise from the gravitational pull between charged objects.

• Electrostatic forces are generated by the imbalance of electric charges due to processes like friction.

What is Coulomb's law in electrostatics?

• Coulomb's law describes the gravitational force between two masses.

• Coulomb's law states that like charges attract each other.

• Coulomb's law only applies to neutral objects.

• Coulomb's law describes the electrostatic force between two charged objects.

How do like and unlike charges interact?

• Like charges repel; unlike charges attract.

• Like charges attract; unlike charges neutralize.

• Like charges attract; unlike charges repel.

• Like charges neutralize each other; unlike charges repel.

What is the unit of electric charge?

• Coulomb

• Ohm

• Volt

• Watt