Motion and Time

Units of Speed

• Meter per second is a unit of speed.

Motion

• An object is in motion when its position changes with time.

Ancient Time Measurement

• A sundial was used to measure time in ancient days.

Uniform Motion

• Uniform motion is movement at a constant speed.

Basic Unit of Time

• The basic unit of time is the second.

Speed Calculation

• Speed is calculated by dividing the distance traveled by the time.

Motion on a Straight Road

• A vehicle moving on a straight road exemplifies rectilinear motion.

Repetitive Motion

• An object repeating its motion after regular intervals exhibits periodic motion.

Distance-Time Graph at Rest

• The distance-time graph of a stationary object is a horizontal line parallel to the time axis.

Pendulum Completion

• The pendulum of a clock takes one second to complete one swing or oscillation.

Speedometer Function

• A car's speedometer measures instantaneous speed, not average speed.

Periodic and Oscillatory Motion

• Periodic motion can be a type of oscillatory motion.

Distance and Displacement

• Distance and displacement are not always equal in magnitude.

Stopwatch Accuracy

• A stopwatch accurately measures time intervals.

Motion and Rest

• Motion and rest are relative terms, depending on the frame of reference.

Defining Speed

• Speed is the rate at which an object covers distance
• Its SI unit is meters per second (m/s).

Uniform vs. Non-Uniform Motion

• Uniform motion involves constant speed, while non-uniform motion involves variable speed.

Simple Pendulum

• Simple pendulum consists of a mass (bob) suspended from a fixed point
• It swings back and forth in periodic motion.

Quartz Clock Accuracy

• Quartz clocks are more accurate due to consistent oscillations of quartz crystal compared to pendulum clocks, which can be affected by external factors.

Sundial Operation

• A sundial tells time by using the position of the sun to cast a shadow on a calibrated dial.

Time Period Measurement Experiment

• Measuring time period of a simple pendulum involves timing multiple oscillations and calculating the average time for one oscillation.
• Factors affecting the time period include the length of the pendulum and the acceleration due to gravity.

Distance-Time Graphs

• Distance-time graphs show how an object's distance changes over time, indicating speed and motion type.
• A straight line indicates uniform speed.

Average Speed Calculation

• To calculate average speed:
  • Total distance traveled is divided by total time taken.
  • In the example: (150 km + 100 km) / (3 hours + 1 hour + 2 hours) = 250 km / 6 hours ≈ 41.67 km/h.

Cyclist's Average Speed

• The cyclist covers a total of 1000 meters in 300 seconds.
• The average speed = 1000 meters / 300 seconds ≈ 3.33 m/s.
• The motion is non-uniform because the cyclist covers the same distance in different time intervals.

Relative Motion Concept

• Relative motion is motion described with respect to a reference point
• Example: a person on a moving train sees stationary objects outside moving backward.
• Specifying a reference point is crucial because motion is perceived differently based on the observer's frame of reference.

Motion in Space

• Determining motion in a spaceship with no external reference involves observing internal changes, like the application of forces or acceleration.
• Without an external reference, constant speed motion is indistinguishable from being at rest.

Explore units of speed and motion with examples like sundials and speedometers. Learn about uniform and periodic motion, and how to calculate speed. Understand distance-time graphs for stationary objects and pendulum motion.