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Graph 2: A car travels at a constant speed of 6 m/s (S = 30 m/5 s). The graph of constant speed is a slanted straight line. Notice that the speed is the same at every point on the graph. How far does the car go in 4 seconds? Variables: S = 6 m/s; t = 4 s; d = ? Formula:
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Graph 2: A car travels at a constant speedof 6 m/s (S = 30 m/5 s). The graph of constant speed is a slanted straight line. Notice that the speed is the same at every point on the graph. How far does the car go in 4 seconds? Variables: S = 6 m/s; t = 4 s; d = ? Formula: Solution:
Graph 3: The same car travels at a constant speedof 1.0 m/s (S = 10 m/10 s). The graph of constant speed is a slanted straight line. Notice that the slope of the line is more gradual and every point on the graph has the same speed. How far does the car go in 4 seconds at its new speed? Variables: S = 1.0 m/s; t = 4 s; d = ? Formula: Solution:
A bike moves 50 m in 10 seconds.Calculate the speed of the bike.
A car travels 200 miles east in 4 hours.Calculate the car’s speed.
A car travels 60 m/s for 10 seconds, north.Calculate how far it traveled.
Acceleration Example: A plane starts at rest and ends up going 200 m/s in 10 seconds. Calculate the acceleration. Step 1: Variables: Vi = starting speed = 0 m/s (“starts at rest”); Vf = ending speed = 200 m/s, ∆t=10s
Deceleration (Negative Acceleration) Example: A race car starts at 400 m/s and then stops in 20 seconds. Calculate the car’s acceleration. Step 1: Variables: Vi =400 m/s; Vf = 0 m/s; ∆t = 20 m/s *** Take note of the negative sign. This represents deceleration or slowing down.
PRACTICE PROBLEMS • A biker starts to move and goes from 0 m/s to 25 m/s in 10 s. What is the acceleration? Variables:
A biker goes from a speed of 20 m/s to 8 m/s in 6 s. What is the acceleration? Variables:
A driver starts his parked car and attains an acceleration of 3 m/s2 in 5 seconds. What is the final speed? Variables: