Physics Notes (PDF)

# Physics ## Date: 23-Aug-24 **Branch of Science that deals with the inter-relationship between matter and energy: ability to do work.** ### Quantities | Physical | Non-Physical | |---|---| | - can be measured | - cannot be measured | | - have a unit | - do not have unit | | - (eg): Lamofos | -...

# Physics ## Date: 23-Aug-24 **Branch of Science that deals with the inter-relationship between matter and energy: ability to do work.** ### Quantities | Physical | Non-Physical | |---|---| | - can be measured | - cannot be measured | | - have a unit | - do not have unit | | - (eg): Lamofos | - (e.g): feelings, emotions | #### Physical Quantities | Basic | Derived | |---|---| | - not made by a combination of other quantities | - made by a combination of basic quantities | ## Date: 23-Aug-24 ### Scalar Quantities - Quantities that do not have direction, only magnitude ### Vector Quantities - quantities that do have direction and magnitude. ## Displacement - Shortest possible distance from one point to another. ## Mass - Amount of inertia in an object. - Mass remains constant. - Is a scalar quantity. ## Weight - The gravitational pull that the earth is applying on an object. - Weight doesn't remain constant. - Is a vector quantity. ## Date: 23-Aug-24 ## Area and Volume - Area of square = L x L - Area of rectangle = L x b - Area of a circle = πR² - Circumference of a circle = 2πR **Calculate the area of a triangle whose base is 4cm and height is 6cm** - B = 4cm - H = 3cm Area of triangle = (b x h)/2 = (4cm x 6cm)/2 = 12 cm² **A triangle has a height of 4 cm and a base of 5 cm. Calculate the area of the triangle.** - (b x h)/2 = (5 x 4)/2 = 10 cm² ## Volume of cube/cuboid = L x b x H ## Volume of a Cylinder = πr²h **Calculate the volume of a block that is 40 cm long, 12 cm wide and 5 cm in which meters.** - ( l x b x h ) = 40cm x 12cm x 5cm = 2400 cm³ **Calculate the volume of a cylinder of 50 cm and height is 25 cm in cubic.** - πr²h = (22/7)(50)²(25) = 1.965625 x 10³ ## Date: 01-10-24 ## Density **Formula:** - Density = mass/volume **Symbol:** ρ **Unit:** kg/m³ or g/cm³ If the density of the object is less than the density of water, the object will float. If the density of the object is more than the density of water, the object will sink. ## Date: - ## Scalars and Vectors ### Scalar Quantity: - Physical quantities which can completely be specified by a number (magnitude) having an appropriate unit are known as scalar quantities. - Scalar quantities do not need direction for their description. - They are comparable only when they have the same physical dimensions. - Two or more than two scalar quantities are equal if they have the same numerical value, even though they are measured in the same system of units and their magnitudes and sign have the same type. - They are denoted by letters in ordinary type. - They are added, subtracted, multiplied, divided by simple values of algebra. ### Examples: - Length of a car is 4.5 m. - Mass of a gold bar is 1 kg. - Time is 1 second. - Temperature is 36.8°C ## Date: 16-10-24 ## Vector Quantities: - Physical quantities having both magnitude and direction with appropriate units are known as vector quantities. - We can't specify vector quantities without mention of direction. - Vector quantities cannot be added, subtracted, multiplied or divided by the simple rules of algebra but instead, the calculations are done by the rules of trigonometry or geometry. - (magnitude + direction) Examples: - Velocity - Displacement - Force - Momentum ## Date: - ## Kinematics - It is the study of speed, velocity, time and acceleration. ### Speed: - Speed is defined as the distance travelled by an object in a given time. Or simply, distance travelled per unit time. - Speed is a scalar quantity while velocity is a vector quantity. - Scalar quantities have magnitude only while vector quantities have both magnitude and direction. ### Example scenario: Consider a car going at a speed of 40, we are not told whether the car is going northwards, down the hill etc. So what is it 40m/s. - It is speed. ## Date: 24-10-2024 ## Calculating Average Speed **Average Speed = (Total distance travelled)/ (Total time taken)** A car travels from town A to town B in 5 hours. The distance between town A and town B is 25 km. What is the average speed of the journey? - Average speed = (25 km)/ (5 hours) = 5 km/h. Another car travels 30 km in 1 hour and then travels another 30 km in 30 minutes. What is the average speed of the entire journey? - Total distance travelled = 60 km - Total time = 1 hour + (30/60) hours = 1.5 hours - Average Speed = (60 km)/ (1.5 hours) = 40 km/h ## Displacement - Displacement is the shortest straight-line distance travelled by an object, regardless of the path length, from the starting point to the final position. ## Date: 29-10-24 ## Acceleration - Acceleration is the rate of change of velocity. - Acceleration = (Final velocity - Initial velocity) / time If an object changes its velocity, we can find its average acceleration by a different formula. **Average velocity = (final velocity + initial velocity) / 2** **a = Δv/Δt** - Acceleration = (Final velocity – Initial velocity)/Time ## Date: 24-10-2024 ## Question | Answers - Speed is a vector quantity. **False** (Scalars and vectors) - Which of the following is a scalar quantity? - Velocity **False** - Force **False** - Time **True** ## Match the following 1. The magnitude of a vector is represented by the numerical value of a quantity. **a - Scalar quantity** 2. A quantity that has both magnitude and direction. **c- Vector quantity** 3. A quantity that has only magnitude. **b- Scalar quantity** 4. The path along which something moves. **d- direction** ## Date: 24-10-2024 ## Explain the difference between displacement and distance. - Distance is a scalar quantity. Displacement is a vector quantity. This is because distance is the total path length covered by an object irrespective of direction. On the other hand, displacement is the shortest possible distance between the starting point and ending point. Example: If we walk on a square path, the distance would be the total length of all four sides, which is 40m. However, the displacement would be 0m as we end up back at the starting point. ## What is the difference between speed and velocity? - Speed is a scalar quantity. Velocity is a vector quantity. This is because speed is distance travelled per unit time, while velocity is displacement per unit time. ## Date: 30 -10 -2024 ## Speed - Speed = Distance / Time If a car travels 300 km in 5 hours, what will be its average speed? - Speed = 300 Km/ 5 hours = 60 km/h. If a car travel is 60km/h for 5 hours, what would be the distance covered? - Distance = speed x time = 60 km/h x 5 hours = 300 km. ## Velocity - Velocity = Change in displacement/ time taken - Velocity unit = km/h or m/s ## Date: 30-10-2024 ## Acceleration - Acceleration = (Final velocity - Initial velocity)/time - Initial velocity = 20 m/s - Final velocity = 50 m/s - Time = 5 sec - a = (50 m/s - 20 m/s)/5 sec = 6 m/s² ## Date: 30-10-24 ## Vector Quantities - They are expressed by using bold letters with arrow signs such as: V, F, A R, etc. - They are represented by a straight line with an arrow head pointing towards the direction of vector.