Class notes
INFORMATIC PRINCIPLESIB-Physics-Core-Notes
- Course
- Institution
INFORMATIC PRINCIPLESIB-Physics-Core-Notes
[Show more]
Seller
Follow
grade_bender
Reviews received
Content preview
Topic 2 Mechanics2.1 Kinematics
2.1.1 Define displacement, velocity, speed and acceleration.
Displacement- Defined as the change in position of an object. Displacement is a
quantity that has both direction and magnitude, it is a vector.
Measured in metres.
Speed- How far an object travels in a given time.
Rate of change of distance (ms-1)
Velocity- The vector version of speed. Tells us the magnitude of how fast an
object is moving and the direction in which it is moving. (ms-1)
Displacement
AverageVelocity =
TimeElapsed
Acceleration- Rate of change of velocity (ms-2)
ChangeInVelocity
AverageAcceleration =
TimeElapsed
2.1.2 Explain the difference between instantaneous and average
values of speed, velocity and acceleration.
Instantaneous values of velocity speed and acceleration are taken at a particular moment. In
any realistic situation they will be constantly varying and is not always meaningful or useful
to know this e.g. drivers need to keep their instantaneous speed below the speed limit.
Average velocity, speed and acceleration are taken over a certain period of time or distance.
E.g. Average speed between Porto and Lisbon = distance/time = 350/km/3 hours 30 min =
100 kmh-1
2.1.3 Outline the conditions under which the equations for uniformly
accelerated motion may be applied.
The following equations of motion may be applied to an object that has a constant
acceleration.
(v − u )
a=
t
s = ut + 12 at 2
v 2 = u 2 + 2as
v= final velocity/ ms-1)
u= initial velocity / ms-1
a= acceleration/ ms-2
s= displacement/m
t=time/s
2.1.4 Identify the acceleration of a body falling in a vacuum near the
Earth’s surface with the acceleration g of free fall.
,Free fall is the uniform acceleration (ignoring the effect of air resistance) in the vertical
direction of an object in a uniform gravitational field. All falling objects have the same
acceleration independent of their masses. On earth all objects accelerate towards the
ground at 9.81 ms-2.
Acceleration due to gravity can be measured in a number of
ways. In the arrangement that is shown a timer starts when
the ball is released form an electromagnet and stops when
the ball passes through a gate at the bottom. The
acceleration due to gravity can then be calculated using:
2s
g=
t2
Acceleration due to gravity can also be calculated using light
gates of ticker timers.
2.1.5 Solve problems involving the equations of uniformly
accelerated motion.
This question is about throwing a stone from a cliff.
Antonia stands at the edge of a vertical cliff and throws a stone vertically
upwards.
v = 8.0ms –1
Sea
–1
The stone leaves Antonia’s hand with a speed v = 8.0ms .
–2
The acceleration of free fall g is 10 m s and all distance measurements are
taken from the point where the stone leaves Antonia’s hand.
(a) Ignoring air resistance calculate
(i) the maximum height reached by the stone.
v 2 = u 2 + 2as
v2
s=
2s
, 82
s=
2 × 10
s = 3 .2 m
(2)
(ii) the time taken by the stone to reach its maximum height.
v−u
a=
t
v−u
t=
a
8
t=
10
t = 0 .8 s
(1)
The time between the stone leaving Antonia’s hand and hitting the sea is 3.0 s.
(b) Determine the height of the cliff.
Time to go form top of cliff to sea = 3.0 – (2 x 0.8) = 1.4s
s = ut + 12 at 2
s = (8.0 × 1.4) + ( 12 × 10 × 1.4 2 )
s = 21m
(3)
(Total 6 marks)
2.1.6 Describe the effects of air resistance on falling objects.
Air resistance acts upon all moving objects. As the velocity of an object increases the size of
the air resistance also increases.
Eventually the force of air resistance will equal the force of gravity. When this happens the
object will stop accelerating. It has reached its terminal velocity.
, The terminal velocity of an object is dependant on its shape. A feather has a lower terminal
velocity than a hammer.
2.1.7 Draw and analyse distance–time graphs, displacement–time
graphs, velocity–time graphs and acceleration–time graphs.
Displacement – time graphs
The object then
is stationary for
12 three seconds.
Object travels at a
10constant speed for the
first five seconds
dispalcement / m
8
The object returns to
6
its original location at a
faster speed.
4
2
0
0 2 4 6 8 10 12
time /s
The gradient of a displacement - time graph is the velocity.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller grade_bender. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.89. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73918 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now