Chapter 2 Form 4 - Tutorial 1 (Physics)
Chapter 2: Forces and Motion – Form 4
2. Linear Motion is motion in straight line
3. Distance is a total length of the path travelled by the object. [SI unit is m] {Distance is a Scalar Quantity}
4. Displacement is the distance travelled in a specific direction. [SI unit is m] (the shortest distance from starting point and the ending point) {Displacement is a Vector Quantity}
5. Speed is the rate of change of distance. [SI unit is ms-1]
6. Velocity is the rate of change of displacement. [SI unit is ms-1]
7. Acceleration is the rate of change of velocity. [SI unit is ms-2]
8. Deceleration is the decreasing of velocity in a period of time. [SI unit is ms-2]
Equation of Linear Motion with Uniform
Acceleration
The various equations
of linear motion of an object with uniform acceleration are given as follows:
*memorize the first
equation.
*the other 3 equations
are given in the Formulae List
Tutorial 2 : Forces and Motion
Newton’s First Law of
motion (Law of Inertia) states that every object will continue in its state of
uniform velocity or at rest unless it is acted upon by an external force.
Inertia is the tendency of an object to remain at rest, or if moving
with uniform velocity, to continue its motion in a straight line.
Mass is measurement for the amount of inertia. A body of greater
mass will have a greater inertia. It has a greater tendency to
maintain its state of motion.
Phenomena of inertia
It is more difficult to push a bucket filled with
sand than an empty bucket because the bucket filled with sand has a greater inertia.
The momentum
is defined as the product of its mass
(kg) and velocity (ms-1)
Momentum is a measure
of motion. It is a vector
quantity (both direction and magnitude). Its direction is the same
as the velocity and its unit is kg m s-1
or N s
Calculation in Collision System and Explosion
1. For elastic collision (Langgar Pisah)
**Kinetic energy also conserve:
2. For inelastic collision (Langgar Lekat)
3. For Explosion
Newton’s Second Law
Motion states
that the rate of change of momentum is directly proportional to applied
force and acts in the direction of the force. F=ma
Force = Mass (kg) x
Acceleration (ms-1)
A push is a
push or a pull. It is a vector quantity (both direction and magnitude) and its
SI unit is Newton (N).
If 2 force F1=F2.
The blocks are either at rest or in uniform
velocity since the forces are balanced or the resultant force is zero.
The gravitational field strength is
defined as force per unit mass acting on the object. Gravitational field
strength,
. The unit for gravitational field strength is
N kg-1
Impulsive
Force is
the force acting on objects in collision or explosion.
Impulse is the product of force and time or the change of momentum. Ft = mv – mu . The SI unit for impulse is Ns or kg m s-1.
There are several safety features installed to a vehicle in order to reduce serious injury to the driver and passengers.
• Bumpers are installed at the front and rear parts of vehicle to lengthen the collision time and to reduce the impulsive force.
• Front or rear part of a car can be crumpled easily in order to lengthen the collision time so as to reduce the impulsive force during an accident.
• An air bag is installed inside the steering wheel of a vehicle. It will inflate just as the car decelerates during an accident. Hence, the head of the driver which surges forward can
be protected.
• Steering wheel of a car is made of material soft enough to lengthen the collision time and cushion the momentum impact of the driver’s head during an accident.
• Dashboard of a car is normally made of material soft enough to lengthen the collision time
when the head of the driver collides at it.
• Windscreen if a car is manufactured in such a way so that during accidents the pieces of the screen chips will not be scattered easily as to hurt the driver or passengers
• The tyre of a car should be broad and with friction grooves so as to control better the stability and the change of momentum of the car
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