Speed, Distance & Time
What type of quantity is distance?
Scalar
Give three example units for measuring velocity
m/s, Km/hr, mi/hr (and direction)
TRUE or FALSE: Displacement requires a direction.
TRUE
Write the units for acceleration.
m/s2
Vector: Velocity and Direction
Draw the speed, distance and time triangle.
Speed = distance / time
1) Speed
2) Direction
Explain how displacement is different from distance.
Distance is the total length of the path traveled by an object, regardless of direction.
Displacement is the straight-line change in an object's position from its starting point to its ending point, including direction.
Write the formula for the final velocity if acceleration is known.
A car's advertised to go from 0 to 60 mph in 6 seconds, what is it's acceleration?
10 mi/hr/s
A car travels 1500 m in 60 s. What is its average speed?
25 m/s
Write the formula for velocity.
Rearrange the velocity to formula to find the displacement.
Displacement = velocity x time
What is the difference between initial and final velocity?
Initial velocity is the starting speed and direction of an object at the beginning of a defined time interval, while final velocity is the object's speed and direction at the end of that same time interval.
I walk my dog from home 7 m north, then turn and walk west 8 m. What is my displacement from home?
10.6 m NW
A cyclist is moving at a constant speed of 8 m/s. How long will it take them to travel 2000 m?
250 seconds
A runner covers 1500 m east in 300 s. What is their average velocity?
velocity = d /t = 1500 / 300 = 5 m/s east
A runner heads in a straight line with a constant velocity of 6 m/s for 50 s. Calculate their displacement.
d = vt
= 6 * 50 = 300m
A car speeds up from 0 m/s to 15 m/s in 5 s.
a = 15/3 = 3m/s/s
Is distance a vector or scalar quantity?
Scalar
A train travels 6000 m at 20 m/s, then 9000 m at 30 m/s. Find the average speed for the whole journey.
T1 = 6000/20 = 300s
T2 = 9000/30 = 300s
300 +300 = 600s
Average speed = total distance / total time = 15000 / 600 = 25 m/s
A student walks 60 m north in 30 s and then 40 m south in 20 s.
Calculate the student’s average velocity.
d = 60 m north - 40 m north = 20 m north
Time = 30 + 20 = 50s
Velocity = D/t = 20/50 = 0.4 m/s north
A cyclist travels east with a velocity of 10 m/s for 120 s, then immediately west at 8 m/s for 150 s.
Find the total displacement from the starting point.
D1 = 10 x 120 = 1200m east
D2 = 8 x 150 = 1200m west
1200 east - 1200 west = 0m
A bike slows down from 12 m/s to 0 m/s in 4 s.
a = -12/4 = -3 m/s/s
What is a frame of reference?
a point in space and time from which to measure motion.