Speed Time and Distance

Explore how speed, time, and distance relate through the formulas distance equals speed times time and speed equals distance divided by time, including common units.

Learn to use conversion factors to transform units, from kilometers and meters to miles and feet, and convert speeds between km/h, m/s, and mph.

Explore basic ratios among speed, time, and distance; see how speed and time are inversely related with constant distance, and how distance varies directly with speed when time is fixed.

This session reinforces basic concepts of speed, time, and distance through practice questions, solving for time and distance using inverse speed-time relationships and ratio methods.

Practice basic speed, time, and distance concepts with worked examples on percentage changes in speed, inverse time relations, and solving for distance and on-time travel.

Compute average speed as total distance over total time, illustrated by 500 miles in 9 hours at 55.5 mph, and two equal periods of time yield the average of speeds.

Learn how to compute average speed when traveling equal distances at different speeds using three approaches and a formula. Then apply the method to unequal distances using distance ratios.

Learn to compute average speed by splitting a journey into distance portions at 40, 60, and 30 km/h, then divide total distance by total time.

Explore the concept of relative speed by analyzing how two moving objects in the same direction differ in speed and how opposite directions sum speeds, with distance and time-based examples.

Apply relative speed to practical questions, showing opposite directions yield a combined speed of 80 mph. Use speed difference for same-direction motion and distance equals to speed into time.

Apply relative speed to solve crossing and catching-up problems. The lecture analyzes two buses starting at 6:00 a.m. and 7:00 a.m. at 40 and 50 km/h, crossing at 11:00 a.m.

Explain how two travelers from opposite ends meet at successive points, detailing distance traveled, first and second meetings, and how speed ratios affect totals.

Explore meeting points when two travelers start from the same end, showing how first and subsequent meetings depend on speed ratios and distances, including the three-to-one case.

Practice meeting point problems using speed and distance ratios to determine where two travelers meet and how first and second meetings relate to total distance.

Explore practical meeting point problems with buses, showing equal speeds meet at the midpoint and solving speed ratios like 5:4 to find the crossing time.

Explore practical meeting point problems using speed, time, and distance concepts. Analyze bus scenarios with equal speeds and inverse relationships to determine when two buses meet.

Explain how two objects starting from opposite ends relate the time before and after meeting, showing inverse speed–time relationships and a square root link to total travel time.

Discuss practical meeting point problems with practice questions, solving for meeting times and speeds from pre- and post-meeting travel data using the concepts presented in the basic session.

Explain train crossing distance: on a bridge or platform, add train length and obstacle length; on a person or pole, use train length alone; on another train, sum both lengths.

Convert 72 km/h to 20 m/s. Crossings follow train-length rules: crossing a man uses the train length; crossing a 300 m bridge takes 25 s for a 200 m train.

Compute the relative speed of trains crossing in opposite directions, convert speeds to meters per second, and determine crossing time from train lengths.

Explore how, with constant time, distance aligns with speed in linear races, and learn terms like beat by 10 meters, head start, and beat by 10 seconds.

Use distance ratios to infer speed ratios in linear race problems, where time is constant; determine how far behind a runner finishes and compute speeds from 100 m race scenarios.

Apply linear basis to solve practical race problems, deriving total distance and speeds from head starts, gaps, and speed ratios in the practice questions.

Explore how two runners on a 300-meter circular track meet by the least common multiple of their round times, and compare first meeting points for same versus opposite directions.

Learn how three or more people moving on a circular track meet on the starting point or anywhere, using the least common multiple of lap times and relative speeds.

On a circular track, opposite directions meet after track length divided by the sum of speeds, and same directions meet after track length divided by the speed difference.

Learn to compute first meeting time for three runners on circular tracks, starting point or anywhere on the track, using speed differences and lcm with 960 m and 600 m.

Learn how the minute and hour hands coincide every 65 5/11 minutes and oppose 11 times in 12 hours, with angles from 0 to 180 degrees.

Learn to find the angle between the clock's hour and minute hands for a given time using 360 degrees per cycle, 30 degrees per hour, and 0.5 degrees per minute.

Clock part 3 shows how to find times when a clock-hand angle is given, reviewing speeds and solving for 60 degrees after 3:00 (5 5/11 and 27 3/11 minutes).

Explore clock time problems by analyzing clocks that gain or lose minutes per hour, and practice computing shown versus actual time with example periods from six am to four pm.

Practice clock angle problems by locating hour and minute positions, applying 30 degrees per hour and 0.5 degrees per minute, and using the non-reflex angle.

Explore clock angle problems by finding times when the hour and minute hands form a given angle, such as 40 degrees between 4:00 and 5:00, and discuss two possible cases.

Explore clock problems by analyzing hour and minute hand angles to determine the departure time between 3 and 4 and the return time between 5 and 6, via two equations.

Learn how river flow and travel direction affect boat speed, using still water and downstream and upstream cases to calculate time from distance divided by speed.

Explore how escalator speed combines with a person’s motion, mirroring boats and streams to illustrate downstream and upstream effects. Compute the effective speed in both matching and opposing directions.

Practice solving boats and streams speed problems using upstream and downstream travel, still-water speed, and current, with practical distance–time examples.

Explore boats and streams and escalators through practical speed–time–distance problems, modeling wind effects on a cyclist and wind-assisted flight to determine speeds and total travel time.

Solve boats and streams and escalator problems through practice questions, deriving speed relations for moving up or down, and calculating escalator speed, time, and stationary step counts.