🧲 • Lesson 3.1 : Motion, Forces and Energy (Phys) Flashcards
In this first physics lesson, you will learn the basics of physical quantities and measurement techniques, motion, mass and weight, and density.
How do you measure time intervals using clocks and digital timers?
Use a clock for continuous time and a digital timer for accurate start/stop times.
What is a scalar quantity?
A scalar has only size (magnitude), like distance, speed, time, mass, energy, and temperature.
What is a vector quantity?
A vector has both size and direction, like force, weight, velocity, acceleration, and gravitational field strength.
How is speed defined?
Speed is the distance travelled per unit time, given by the equation v = s/t.
How do you calculate average speed?
Average speed = total distance travelled / total time taken.
What is velocity?
Velocity is speed in a given direction.
What is acceleration?
Acceleration is the change in velocity per unit time, given by a = Δv / Δt.
How do you sketch, plot, and interpret distance–time and speed–time graphs?
Distance–time: Steeper slope = faster motion.
Speed–time: Horizontal line = constant speed, slope = acceleration/deceleration.
How can you tell from a distance–time graph if an object is at rest?
A horizontal line indicates the object is at rest.
How can you tell from a distance–time graph if an object is moving with constant speed?
A straight, diagonal line indicates constant speed.
How can you tell from a distance–time graph if an object is accelerating, and decelerating?
Accelerating : Curved line with increasing steepness.
Decelerating : Curved line with decreasing steepness.
How can you tell from a speed-time graph if an object is moving with constant acceleration?
Straight, sloping line.
How can you tell from a speed-time graph if an object is moving with changing acceleration?
Curved line.
How do you calculate speed from a distance–time graph?
Speed is calculated from the gradient (slope) of a straight-line section:
Speed = distance / time.
How do you calculate acceleration from a speed–time graph?
Acceleration is calculated from the gradient of a straight-line section:
Acceleration = change in velocity / time.
How do you calculate the distance travelled using a speed–time graph for motion with constant speed?
The area under the speed–time graph is a rectangle:
Distance = speed × time.
How do you calculate the distance travelled using a speed–time graph for motion with constant acceleration?
The area under the speed–time graph is a triangle:
Distance = ½ × (initial speed + final speed) × time.
What is the acceleration of free fall near Earth’s surface?
The acceleration of free fall g is approximately 9.8 m/s².
What is mass?
Mass is a measure of the quantity of matter in an object.
What is weight?
Weight is the gravitational force acting on an object due to its mass.
What is gravitational field strength (g)?
Gravitational field strength g is the gravitational force per unit mass.
Equation: g = W/m (where W is weight and m is mass).
Near Earth’s surface, g ≈ 9.8 N/kg.
What is the relationship between gravitational field strength and acceleration of free fall?
Gravitational field strength is equivalent to the acceleration of free fall near Earth’s surface.
What is density?
Density is mass per unit volume.
Equation: ρ = m/v (where ρ is density, m is mass, and V is volume).
How do you determine the density of a liquid?
Measure the mass of the liquid, then measure its volume using a suitable container (like a measuring cylinder), and apply the equation ρ = m/v.
How do you determine the density of a regularly shaped solid?
Measure the mass of the solid, then calculate its volume based on its dimensions (length, width, height, etc.), and apply ρ = m/V.
How do you determine the density of an irregularly shaped solid that sinks in a liquid?
Measure the mass of the object. Submerge the object in a liquid, and use displacement to measure the volume of the object (the volume of liquid displaced equals the object’s volume).
Then apply ρ = m/v.
How can you determine if an object will float or sink based on density?
If the object’s density is greater than the density of the liquid, it will sink. If the object’s density is less than the liquid’s density, it will float.
