Physics Class on Quantities and Motion

Physical Quantities and Units

• SI unit of luminous intensity: Candela
• Derived physical quantity: A physical quantity that can be expressed in terms of fundamental physical quantities
• Fundamental physical quantity: A physical quantity that cannot be defined in terms of other physical quantities

Significant Figures

• Rounding off: The process of reducing the number of digits in a number while keeping its value as close to the original as possible.
• Significant figures represent the reliable digits in a measurement.

Motion and Kinematics

• Velocity-time graph: A graph plotting velocity against time.
• Slope of a velocity-time graph represents acceleration.
• Instantaneous speed: The speed of an object at a particular moment in time.

Vectors and Scalars

• Equal vectors: Two vectors are equal if they have the same magnitude and direction.
• Angle between two equal vectors: 0°

Projectile Motion

• Projectile motion: The motion of an object projected with an initial velocity and then subjected to only the force of gravity
• Horizontal range: The horizontal distance traveled by a projectile.
• Doubling the initial speed: Doubles the horizontal range, keeping the angle of projection constant.

Elasticity

• Elasticity: The ability of a material to regain its original shape after the deforming force is removed.
• Steel: More elastic than rubber.
• Deforming force: A force that causes a material to deform.

Stress

• Stress: Force per unit area acting on a material.
• Dimension formula of stress: $ML^{-1}T^{-2}$