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Velocity and Other Rates of Change. 3.4. B. distance (miles). A. time (hours). (The velocity at one moment in time.). Consider a graph of displacement (distance traveled) vs. time. Average velocity can be found by taking:.
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B distance (miles) A time (hours) (The velocity at one moment in time.) Consider a graph of displacement (distance traveled) vs. time. Average velocity can be found by taking: The speedometer in your car does not measure average velocity, but instantaneous velocity.
Instantaneous Velocity Velocity is the first derivative of position.
Gravitational Constants: Example: Free Fall Equation
Acceleration is the derivative of velocity. example: If distance is in: Velocity would be in: Acceleration would be in:
distance time It is important to understand the relationship between a position graph, velocity and acceleration:
Speed • Speed is increasing if a(t) and v(t) have the same sign. • Speed is decreasing if a(t) and v(t) have a different sign.
Average rate of change = Instantaneous rate of change = Rates of Change: These definitions are true for any function. ( x does not have to represent time. )
Example a. Find the of change of the area A of a circle with respect to its radius r. • Evaluate the rate of change of at r = 5 and at r = 10. • If r is measured in inches and A is measured in square inches, what units would be appropriate for dA/dr.
Example A dynamite blast propels a heavy rock straight up with a launch velocity of 160 f/s. It reaches a height of s = 160t-16t2 ft after t seconds. • How high does the rock go? • What is the velocity and speed of the rock when it is 256 ft above the ground on the way up and on the way down? • What is the acceleration of the rock at at any time t during its flight? • When does the rock hit the ground?
from Economics: Marginal cost is the first derivative of the cost function, and represents an approximation of the cost of producing one more unit.
Note that this is not a great approximation – Don’t let that bother you. The actual cost is: Example 13: Suppose it costs: to produce x stoves. If you are currently producing 10 stoves, the 11th stove will cost approximately: marginal cost Marginal cost is a linear approximation of a curved function. For large values it gives a good approximation of the cost of producing the next item. actual cost