P2.1 - Motion Flashcards
State different ways to measure time (and cons)
\+ use a stopwatch \+ use a light gate cons? there is a reaction time that affects the accuracy and precision is expensive to buy
What is the equation for calculating average speed?
total distance (m)
average speed (m/s) = ————————
total time (s)How many meters are there in one mile?
1609m
What is the difference between a scalar and a vector measurement?
Vector has a magnitude (size) and direction -> represented as an arrow ie. force
Scalar has only magnitude (size) but no direction.
ie. time on a stopwatch (10s)
What is displacement and is it a vector or scalar?
+ The distance from the place you travel
+ is a vector (has direction)
What is speed?
+ a scalar quantity (has no direction)
+ is a measurement
ie. 15m/s
What is velocity?
+ A vector quantity
+ has a direction as well as a magnitude
ie. 15m/s south
+ is in a certain direction
What is the change in velocity per second called?
acceleration
what is the equation for acceleration?
change in velocity (m/s)
acceleration (m/s^-2) = ——————————
time (s)
What is the term when a vehicle slows down (acceleration)?
deceleration
What does a (diagonal) straight line mean on a distance time graph?
the object’s speed is constant because the gradient doesn’t change
What does a horizontal line mean on a distance time graph?
the object is not moving
What does a steep line mean on a distance time graph?
The steeper the line, the faster the object is travelling
How do you calculate speed from a distance time graph?
1) Draw a right-angled triangle underneath the line
2) Find the change in distance and the change in time
3) Use the equation of speed to find out the answer
What is the difference between a distance-time graph and a displacement-time graph?
+ a distance-time graph is scalar
+ a displacement-time graph’s gradient has a velocity
what is the equation for velocity?
change in displacement
velocity = ——————————
time
What does the gradient on a graph tell you?
the rate of change with time
what does the change of speed or velocity tell you?
acceleration
if the initial velocity is higher than the final velocity, how is the acceleration shown?
as a minus number
ie. -0.35 m/s^2
What is the equation of motion?
v^2 - u^2 = 2as
What is the equation to calculate kinetic energy?
kinetic energy (J) = 0.5 x mass (kg) x speed (m/s))^2
If a question says that an object is at rest, what is its initial velocity?
0 m/s^2 (since it is not moving)
bro said m/s^2 how did this girl pattern up to get a grade 9
- if she can do it anyone can
Convert 30mph to m/s
1 mile = 1609m
1hr = 60m
60m = 3600s
d 48 270
s = —— = ————
t 3 600
= 13m/sHow many seconds are there in an hour?
3600
How do you represent a vector?
With an arrow (length shows magnitude)
what is the unit of acceleration?
m/s^2
how is an object moving if it has a negative velocity?
In the opposite direction
How do you figure out the speed on a distance-time graph?
Look at the gradient (speed is equal to gradient)
what does a horizontal line mean on a distance-time graph?
that the object is not moving
how do you calculate speed on a distance time graph?
draw a right-angled triangle and divide the change in distance by change in time
how is a distance time graph different from a displacement time Graph?
- A distance time graph only shows the total distance travelled
- on displacement time graph, the gradient can be negative
what does the gradient represent on a displacement time graph?
the velocity of an object
how do you calculate acceleration from a velocity-time graph?
change in velocity
————————
change in time
how do you calculate distance travelled on a velocity time graph?
measure the area below the line
what unit is velocity measured in?
m/s
what unit is kinetic energy measured in?
Joules (J)
What is human reaction time?
0.2s
describe in detail how to measure your walking speed
- measure the distance you walked
- divide it by the time taken to walk that distance
Why does kinetic energy quadruple when the speed is squared?
Because it is relative to double the speed of the object (so 2x2 =4)
Is acceleration a vector or a scalar?
A vector, as it is the rate of change in VELOCITY not speed.
So if an object is at a constant speed, but changing direction, it is still accelerating
If a body is moving and it starts to slow down, is it still accelerating?
Yes, as it has changed it’s speed
state methods to measure distance:
metre ruler
tape measures
ultrasound? (bit far-fetched but ig it works)
