Speed Problems
What is the equation for speed?
Speed = distance/time
In a motion graph, what are the correct labels for the Y-axis and X-axis?
Y-axis = Distance
X-axis = time
What does it mean for an object to accelerate?
To change its speed in a certain amount of time.
What are 3 common units for time in science?
Hours, minutes, seconds.
What is the equation to find acceleration?
A = (S2 - S1)/ t
A runner jogs 5 km in 21 minutes. What is the speed of the runner?
S= 5km/21min = 0.24 km/min.
How do you find speed on a distance-time graph?
Speed = d/t = rise/run = slope
Speed = slope on a distance-time graph!
A motorcycle and a tractor trailer can accelerate to 60 mph from rest. Explain which vehicle has the greater acceleration and why.
The motorcycle has a greater acceleration because while the change in speed is the same for both the motorcycle does it in a shorter time.
What are 3 common units for distance in science?
Kilometers (km), meters (m), centimeters (cm)
A swimmer can swim at a speed of 3 m/s for 5 minutes. What distance will she cover in that time?
5 minutes = 300 sec.
d= s x t = 3 x 300 = 900 m
A car travels 100,000 m in 1 hour. What is the speed of the car in m/s?
S= 100,000/ 3,600 = 27.8 m/s
What is the speed of an object from 0 to 10 hours?
(See Graph Worksheet)
S = d/t = rise/run
S= 10 km/10hrs = 1 km/hr
An ice skater increases his speed from 4.0 m/s to 12.0 m/s in 2.0 seconds. What is the skater’s acceleration?
A = (S2 - S1)/ t = (12 - 4)/2 = 4 m/s2
What are 3 common units for speed in science?
km/hr, m/s, cm/s
A rollerblader traveling at 7.0 meters per second rolls to a stop at the top of a ramp in 3.0 seconds. What is the rollerblader’s acceleration?
A = (S2 - S1)/ t = (0-7)/3= -2.33 m/s2
A Category 5 hurricane is the fastest type of hurricane with speeds up to 70 m/s. If the Category 5 hurricane is 2 miles (3,200 m) off shore, how long do you have until the hurricane reaches the shore?
t = d/s = 3,200/70 = 45.7 s
When was the runner stationary?
(See Graph Worksheet)
The runner was stationary at Stages B-C and D-E because it was a flat line (slope = 0).
A car traveling at a speed of 30.0 m/s encounters an emergency and comes to a complete stop in 7.5 seconds. What is the deceleration of the car?
A = (S2 - S1)/ t = (0-30)/7.5= -4 m/s2
m/s2 , or m/s/s , or metes per second per second
What is Mr. G's middle name?
Edward
Usain Bolt's top speed was recorded at 27 mph (12.3 m/s) when he sprinted 40 meter dash. How long did it take him to finish the race?
t = d/s = 40/12.3 = 3.25 seconds
When was the runner traveling the fastest? Be sure to show your work.
Speed at C-D = 9 km/4 hrs = 2.25 km/hr
Speed at E-F = 12 km/6 hrs = 2 km/hr
So C-D is the fastest.
As she climbs a hill, a runner slows down from 4 m/s to 2.5 m/s in 4 minutes. What is her deceleration? (Hint: Make sure your units match)
A = (S2 - S1)/ t = (2.5 - 4)/240 = -0.006 m/s2
How do we measure speed in science class?
How many teeth do humans have?
32...can you count them all? =)