assessment 2 - physics
0 - 70 / 7 = 70 /7 = 10 m/s 2
A car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds. Find the car's average acceleration.
1st car: 8 / 3 = 2.67 m/s 2 2nd car: 30 / 8 = 3.75 m/s 2 no, the acceleration of the second car is higher
A cyclist accelerates from 0 m/s to 8 m/s in 3 seconds. What is his acceleration ? Is this acceleration higher than that of a car which accelerates from 0 to 30 m/s in 8 seconds?
15 / 2 = 7.5 m/s 2
A cyclist in the Tour de France accelerates down a hill from 22 m/s to a speed of 37 m/s. This acceleration takes him 2 seconds. Calculate the acceleration
58 m/s
A man skis down an 1160 m run in 20 seconds - how fast does he go?
14 / 2 = 7 m/s 2
Change in speed = 14 m/s; time taken = 2 seconds. Calculate the acceleration
^P = p x g x ^h
solve
465 m
How far can a cheetah run in 15 seconds at 31 m/s?
8100 m
How far could you cycle in 30 minutes, moving at 4.5 m/s?
1.05 m/s
How fast does a giant tortoise travel if they covered 45m in 43 s.
89 s
How long does a Tuna travelling at 18m/s take to go 16km?
50 x 3 = 150 150 + 10 = 160 (final velocity)
If a Ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 50 m/s2 for 3 seconds, what will its final velocity be?
230 s
Raindrops fall at 9m/s. How long do they take to fall from a cloud 2070m from the ground?
the speed something is moving at a particular point in time
What is instantaneous speed?
change in y/change in x 10/10 1 m/s 2
calculate the acceleration in C
change in y / change in x 25/20 1.25 m/s 2
calculate the acceleration in D
person starts journey
describe what happens at point A
person is stationary
describe what happens at point B
person is stationary
describe what happens at point C
turns around
describe what happens at point D
arrives at location
describe what happens at point E
constant velocity (speed is not changing)
describe what is happening at line C
constant deceleration (speed is decreasing at a constant rate)
describe what is happening at line D
stationary
describe what is happening at line D
constant acceleration (speed is increasing at a constant rate)
describe what is happening at lines A and B
change in y/change in x (0,0) (3,15) 15/3 5 m/s
find the speed over 0-A
change in y/change in x (3,15) (8,15) 0/5 0 m/s
find the speed over AB
change in y/change in x (8,15) (12,0) 15/4 3.75 m/s
find the speed over BC
0-2 0-12 2/12 6
find the speed, if a line were to have a point at 0,0 and another at 2,12
rectangle: bh = 2 x 20 = 40 triangle: 1/2 bh = 1/2 5 x 20 = 50 40 + 50 = 90 m
find the stopping distance on this graph
you find the gradient gradient = change in y / change in x
how do you calculate speed from a distance x time graph?
you find the area of the line
how do you find distance on a speed x time graph
1. separate each line into a shape 2. find the area of each shape 3. add the areas up together
how would you calculate stopping distance on a graph
gradient = change in y/change in x 10/10 1 m/s 2
how would you find the acceleration of line B?
1. split into two shapes (triangle and rectangle) 2. find the area of each (1/2bh + bh) (1/2 10 x 10 + 10 x 15) (50 + 150) (200 m)
how would you find the distance moved at line B?
Na 2 or Pa
what are the units used for pressure?
change in
what does "^" mean in a formula
you are going towards the starting position
what does a downward slanted line on a distance x time graph mean?
its means the object is not moving, it is stationary
what does a straight line that is not on the x-axis mean on a distance x time graph?
you are going away from the starting position
what does an upward slanted line on a distance x time graph mean?
the average speed something is moving during the whole journey
what is average speed?
stopping distance = thinking distance + braking distance
what is stopping distance
the time between applying the breaks and stopping
what is the braking distance
speed is a scalar meaning it only has size, but velocity is a vector meaning it has both and direction
what is the difference between speed and velocity?
line A and line B are both accelerating, but line A is accelerating at a faster rate because it is steeper
what is the difference between what is happening at line A vs line B?
line A is going faster than line B because it steeper
what is the difference between what is happening at line A vs line B?
change in velocity (speed) / change in time final velocity-starting velocity / final speed-starting speed
what is the formula for acceleration
density = mass/volume
what is the formula for density?
distance = speed x time
what is the formula for distance?
change in y / change in x
what is the formula for finding acceleration on a speed x time graph
force ___________________________________ pressure x area
what is the formula for pressure when it is involving air or a solid?
^P (change in pressure) = p (density of fluid) x g (gravitational field strength) x ^H (change in height)
what is the formula for pressure when it is involving depth (water)?
speed = distance / time
what is the formula for speed?
time = distance / speed
what is the formula for time?
change in velocity = acceleration x time
what is the formula to find a change in velocity?
change in velocity = acceleration x time change in velocity + initial velocity = final velocity
what is the formula to find the final velocity when involving acceleration?
the time between seeing the hazard and applying the breaks
what is the thinking distance
m/s 2
what is the unit for acceleration
kg/m 2
what is the unit for density?
m
what is the unit for height?
m/s
what is the unit for speed
m/s
what units do we measure speed in?
