PRACTICE TEST QUESTIONS WITH EXEMPLAR
ANSWERS
◉ Velocity. Answer: Is a vector and therefore has both direction and
magnitude.
=displacement / time
◉ Accelaration. Answer: =(v-u)/t
Where v is initial velocity and u is final velocity
◉ Displacement time graph. Answer: upward slope - constant
positive velocity
flat line - stationary
downward slope - negative constant velocity
It can often be easier to just draw a distance-time graph.
◉ velocity-time graph. Answer:
◉ Acceleration-time graph. Answer: a graph describing motion of an
object, with acceleration on the vertical axis and time on the
horizontal axis.
,upward slope - increasing acceleration
flat line - constant acceleration
downward slope - decreasing acceleration
◉ Adding vectors. Answer: Draw both vectors next to each other
head to tail and then use Pythagoras and/or trig to calculate the
missing side of the triangle and the angle.
Remember, in order to draw these correctly, you'll probably have to
move one of the vectors.
◉ Moments. Answer: the turning, movement of a force.
=force x perpendicular distance from the pivot.
◉ Principle of moments. Answer: For an object that is in
equilibrium:
- the sum of the clockwise moments = the sum of the anticlockwise
moments
- There is no resultant force.
◉ Centre of gravity. Answer: The point where the entire weight of an
object appears to act.
This is essentially the same thing as the centre of mass
This always lies along the line of symmetry. for a flat irregular object
hang it from different points and draw a line straight down. Where
,the lines connect that's the centre of mass, because it will always
hang directly under a point of suspension.
For other irregular objects it can be found using moments.
◉ Newton's First Law. Answer: An object at rest stays at rest and an
object in motion stays in motion with the same speed and in the
same direction unless acted upon by an unbalanced force.
◉ Newton's Second Law. Answer: F=ma
◉ Newton's Third Law. Answer: For every action there is an equal
and opposite reaction
◉ Kinematics. Answer: s = displacement
u = initial velocity
v = final velocity
a = acceleration
t = time.
All of the equations apart from s = (u+v)/2 xt are given in the
formula book. Just use them.
, ◉ Resolving vectors. Answer: A single diagonal vector can also be
broken down into it's horizontal and vertical components. The
principle is the same as when finding resultant vectors.
◉ projectile motion. Answer: When objects are thrown up into the
air or kicked off a cliff or something similar, they move in a curved
line.
By separating the horizontal and vertical components of this motion
we can calculate distances, times and velocities etc.
The vertical component just goes straight up and down and has
acceleration due to gravity.
◉ gravitational potential energy. Answer: The energy that an object
has by virtue of it's position in a gravitational field.
= mgh
◉ Kinetic energy. Answer: the energy an object has by virtue of its
movement
= ½mv²
◉ Transfer of energy. Answer: When an object falls, gravitational
potential energy is converted into kinetic energy. This happens as
energy must be conserved.