Transcript Chapter 2 Lessons 1 - 3 slides

Kinematics in 1 dimension with constant acceleration
Lesson Objective: The ‘suvat’ equations
Consider a point mass moving along a line
with a constant acceleration.
What does its velocity time graph look like?
s = ut + ½at2
v = u + at
v2 = u2 + 2as
Note:
When using these equations
pick a direction for positive
and stick to it!
s = ½(u + v)t
a = acceleration
u = initial velocity
(velocity at the start of a time period specified by you)
v = final velocity
(at the end of the time period specified by you)
t = time
s = displacement (not distance)
A car accelerates from rest at 5ms-2. How long does it take for
the car to travel 100m and what is the velocity at that instant?
A bus leaves a bus stop by accelerating at 0.8ms-2 for 5s. It then
travels at a constant speed for 2 minutes before slowing down
uniformly at 4ms-2 to come to rest at the next bus stop.
a) Find the constant speed in the middle part of the journey
b) Find the distance travelled in the first part of the journey
c) Find the total distance between the two bus stops
A particle positioned at O is travelling at 20ms-1.
It starts to decelerate at a constant rate of 3ms-2 and continues to
do so for 12 seconds.
a) Find the time taken for the particle to come instantaneously to
rest.
b) Find the final velocity of the particle.
c) Find the position of the particle relative to O at the end of the
journey.
d) Find the distance travelled in the entire 12 seconds
A particle moves in a straight line from O to A with a constant
acceleration of 2ms-2. Its velocity at A is 30ms-1 and it takes 12
seconds to travel from O to A. Find the particles velocity at O
and the distance OA.
A train starts from rest at a station S and moves with constant
acceleration. It passes a signal box B 15 seconds later with a
speed of 81kmh-1. Find the acceleration of the train in ms-2 and
the distance in metres between S and B.
A, B and C are three points that lie in that order on a straight road
with AB = 95m and BC = 80m. A car is travelling along the road
in the direction ABC with constant acceleration ‘a’ ms-2. The car
passes through A with speed ‘u’ ms-1, reaches B 5 seconds later
and C 2 seconds after that. Find u and a.
Kinematics in 1 dimension with constant acceleration
Lesson Objective: The ‘suvat’ equations and gravity
Dissatisfied with the quality of his Chinese meal, an oriental
tourist drops his plate from a rooftop restaurant, 100m above
the ground. How long does it take for the chop suey to hit the
ground, and at what speed is it then travelling?
A juggler throws a ball up in the air with an initial speed of
5ms-1 from a height of 1.2m. Assuming that g is 10ms-2, find
the maximum height that the ball reaches above the ground and
the time it takes to reach this height.
A juggler throws a ball up in the air with an initial speed of
5ms-1 from a height of 1.2m. Assuming that g is 10ms-2, find
the maximum height that the ball reaches above the ground and
the time it takes to reach this height.
Find the time taken for the ball to hit the ground if the juggler
fails to catch it.
A juggler throws a ball up in the air with an initial speed of
5ms-1 from a height of 1.2m. Assuming that g is 10ms-2, find
the maximum height that the ball reaches above the ground and
the time it takes to reach this height.
Find the time taken for the ball to hit the ground if the juggler
fails to catch it.
When the first ball reaches its maximum height the juggler
throws another ball with the same speed and from the same
height. Where and at what time will the balls collide/pass each
other?
Forces
Lesson Objective:
Understand the types of Forces that exist and Newton’s third law
Types of Force
Weight
Normal Contact
Friction
Driving Forces
Resistance Forces
Tension Forces
Cause
Direction
Gravity pulling
Towards the ground
Something touching
Perpendicular to
the surface
Where there are rough
surfaces in contact
In opposite direction
to the movement
Motors or Engines
In same direction as
the movement
Fluids
In opposite direction
to the movement
Pulling with a string/bar
Along the line of
the string/bar
Newton’s Third law states:
When one object exerts a force on another there is always a
reaction of the same kind which is equal and opposite in direction
to the acting force.
Newton’s first law:
Every body continues in a state of rest or in a a state of
uniform motion in a straight line unless acted on by a resultant
force