Motion
Reference Point and Reference Frame
To talk about where something is, we need a starting point called a reference
point. For example, imagine sitting in a bus—inside, it might seem like everyone
is still, but if someone outside looks, they'll see the bus and everyone inside
moving.
Distance and Displacement
Distance: How much ground something covers, but it doesn't care which
way. Like counting steps without knowing where you're going.
Displacement: How far something is from where it started and in which
direction. It's like saying you're 5 steps away and to the right.
Magnitude
Scalar quantities: Things with only size, like time or temperature.
Vector quantities: Things with both size and direction, like velocity (how fast
something is moving) or force.
Time, Average Speed, and Velocity
Time: How long something takes, measured in seconds.
Average Speed: How much ground is covered on average in a certain time.
Velocity: Like speed, but also tells you which way something is going.
Uniform Motion and Non-Uniform Motion
Uniform Motion: When something covers the same amount of ground in the
same time intervals, like a spinning fan or the Earth moving around the sun.
Non-Uniform Motion: When something covers different amounts of ground
in the same time intervals, like a bouncing ball or a running horse.
Velocity
Velocity is like speed but with direction. Instantaneous velocity is your speed at
one moment, while average velocity looks at your overall speed for the whole
trip.
Acceleration
Acceleration means how quickly something's speed is changing. It's like when a
car goes from being still to moving or speeds up or slows down.
We use the symbol "a" for acceleration, and it's calculated by dividing the
change in velocity by the time it takes.
Distance-Time Graph
Graphs help us see how things move. In a distance-time graph, if the line is
straight, it means the object is moving at a steady speed. The slope
(steepness) of the line tells us about the speed.
Velocity-Time Graph
Another kind of graph shows how velocity changes over time. If the line goes up,
the object is speeding up. If it goes down, it's slowing down. The slope of the
line shows acceleration.
Equations of Motion
Uniform Circular Motion
This happens when something moves in a circle at a steady speed. Like a
satellite going around Earth or the tip of a clock's second hand. The speed
stays the same, but because it's going in a circle, the direction keeps changing.
These formulas help us understand it.
Exemplar problems
