Linear Motion
You are walking and travel 75 meters in 25 seconds. What is your average walking speed?
3 m/s
Draw a position vs time graph at rest
horizontal line on graph
What does the slope of a velocity vs time graph give you?
acceleration!
What is g and what is its value?
acceleration due to gravity! 9.8 m/s^2 (10 is ok)
Why do we say that velocity is a "vector" quantity and speed is a "scalar" quantity?
velocity depends on the magnitude (how fast) and the direction making it a vector. Speed is only "how fast" so it is a scalar
What is the average speed you are traveling if you go 15m in 3 sec?
5 m/s
Draw a position vs time graph of an object moving in the positive direction while speeding up
positive slope that is increasing
What does the slope of a position vs time graph give you?
velocity!
If an object is thrown upwards, how much speed does it lose each second? Ignoring air resistance.
10 m/s for each second
Can you maintain constant speed while rounding a corner? What about constant velocity? Defend your answer
Speed: yes. direction does not matter with speed
Velocity: no. constant velocity is maintaining constant speed and direction
What is the distance you travel if you have an average speed of 50 m/s and are walking for 4 sec?
200 m
Draw a velocity vs time graph where the velocity is positive and the acceleration is negative
line with negative slope above the x axis
How do you calculate the displacement of an object in a velocity vs time graph
calculate the area under the curve
If an object is falling, how fast is it going at 2 seconds? What about 4 seconds?
2 sec: 20 m/s
4 sec: 40 m/s
How do you calculate the average velocity of an object?
vf + vi / 2
(take the average of the two velocities)
If you walk 0.8 m at an average speed of .04 m/s , how long were you traveling for?
20 sec
Draw a velocity vs time graph where the velocity is negative and the acceleration is positive
line that is below the x axis with a positive slope
How do you tell an object changed direction when looking at a velocity vs time graph?
When it crosses the x-axis
Why do we have to double the time calculated in the hang time activity to truly calculate your hang time?
Your calculation gave the time for just the way up, but you double it because you also come back down
Explain the difference between distance and displacement. Which is a scalar quantity and which is a vector quantity?
distance is just how far (scalar) and displacement is relative to the starting position (distance and direction)
What is the acceleration of a bike moving in a straight path that increases its speed from 0 to 30 m/s in 12 sec?
2.5 m/s^2
Draw a velocity vs time graph that is maintaining constant positive velocity
horizontal line above the x axis
What is the acceleration of an object given these two data points from a velocity vs time graph:
initial: (5,10) final: (10,0)
-2 m/s^2
A lizard falls off a fence, and hits the ground in 1.25 seconds.
1. What is his velocity when he hits the ground?
2. What is the average velocity of his fall?
3. How tall is the fence?
1. 12.25 m/s
2. 6.125 m/s
3. 7.8125 m
rearrange the equation: d=1/2gt^2 to solve for t. Show your work
t= sqrt(2*d / g)