Kinematics Flashcards
Scalar Quantity
Physical quantity having magnitude only.
Vector Quantity
Physical quantity having both magnitude and direction.
Ways to state direction of vector
- Angle with respect to horizontal/ vertical
- Left/right/upwards/downwards
- North, Southeast
Distance, S
Total length covered by a moving object regardless of the direction of motion
Displacement, S
Distance measured in a straight line in a specific direction
Speed, v
Rate of change of distance
Velocity, v
Rate of change of displacement
Average speed, v
Total distance divided by total time taken
Instantaneous speed, v
Speed at a particular instant
Acceleration, a
Rate of change of velocity
Acceleration occurs when
there is a change in speed
there is a change in direction
there is a change in speed and direction
Description of free-fall object
- At the instant when the object is released, the weight is the only force acting on it. Hence, the object accelerates downwards at 10m s^-2.
- The object acquires a downward speed and it now experiences air resistance acting downwards. This causes the net force downwards to decrease and hence the downward acceleration decreases due to Newton’s Second Law of Motion.
- As the velocity of the object increases, the air resistance increases, causing the net force downwards and the downward acceleration to decrease further. The velocity increases at a decreasing rate.
- Eventually, when the force due to air resistance becomes equal in magnitude to the weight of the object, the net force acting on the object, and hence its acceleration becomes zero. The object reaches terminal velocity.
Terminal velocity
The constant and maximum velocity of a falling object.
Equations of motion
a = (v-u)/t
s= 1/2(u+v)t
s=ut + 1/2at^2
v^2=u^2 + 2as
