We know from observations that objects are in a constant state of motion. Objects can be stationary (speed is zero), or move with a constant speed or with a changing speed. We also have the concepts of average speed and instantaneous speed. Suppose a person drives a car from Brooklyn to Albany (in normal traffic and stopping for gasoline), a distance of 120 miles, in 4 hours. The average speed is 30 miles per hour. The instantaneous speed refers to the speed at a particular instant in time.
The average speed (v) is defined as the distance (s) traveled by the object divided by the final (f) time minus the initial (i) time:

avgvel



The instantaneous speed can be defined with the help of calculus as the average speed with an infinitesimally small time interval.

  1. A motorist travels 460 km during a 7 hour period. What was the average speed?
  2. During a canoe race, a camper paddles 406 meters in 70 seconds. What is the average speed?
  3. A bullet is shot from a rifle with a speed of 720 m/s. What time is required for the bullet to strike a target 3240 m away?
  4. How far will an object move in one second if its average speed during that second is 5 m/s?
  5. Does the speedometer of a car read instantaneous speed or average speed.
  6. What two controls on a car enable a change in speed?