P5 - Forces Flashcards
What is the difference between a
vector and a scalar?
A vector quantity has magnitude and a direction but a scalar quantity only
has a magnitude.
What are forces?
Forces are either pushes or pulls
What do forces do?
Forces cause objects to accelerate.
This means their speed changes.
If the resultant force on an object is zero what does this tell you?
If the resultant force is zero then
the object will not accelerate.
The speed will NOT change. It could
be stationary OR moving with a
constant speed.
What is Hooke’s law?
The extension of a spring is directly
proportional to the force applied, as
long as its limit of proportionality is
not exceeded
How do you calculate the
extension of a material?
The extension of a spring is found by
subtracting the original length from
the extended length.
Extension = extended length – original length
If the forces on an object
are unbalanced what does this
tell you?
The object will accelerate in the
direction of the resultant force
What is the definition of
centre of mass?
The centre of mass of an object is
the point at which its mass can be
thought of as being concentrated
What does the parallelogram
of forces allow you workout?
The parallelogram of forces allows you
to work out the resultant force on an
object
What does resolving a
force mean?
When you resolve a force you separate the force into 2 perpendicular components
What is the equation for speed
and what is the unit?
Speed = distance ÷ time
v=s/t
The unit is m/s
What does the gradient of a
distance-time graph represent?
The speed of the object
What is the difference between
displacement and distance?
Displacement is a vector (magnitude
and direction) and distance is a
scalar (just magnitude)
What does the gradient of a
velocity-time graph represent?
The acceleration of the
object
What is the equation for
acceleration and what is the
unit?
Acceleration = change in velocity ÷ time
The unit is m/s²
How do you calculate
the gradient of a curved line?
1 – Draw a tangent to the curve
2 – Calculate the gradient of the tangent
What does the area under a velocity-time graph represent?
The area under a velocity-time graph is equal to the distance travelled.
What do the letters in this equation represent?
v²-u² = 2as
s = distance
u = initial velocity
v = final velocity
a = acceleration
What is the definition of inertial
mass and what is inertia?
Inertial mass is a measure of how difficult it is to change the velocity of an object.
Inertia is the tendency of objects to continue in their state of rest or of uniform motion.
Inertial mass is defined as:
force ÷ acceleration
What is Newton’s 2nd law?
Newtons 2nd law states that the
acceleration of an object is directly
proportional to the force and inverse
What is the equation for weight?
Weight = mass x gravitational field strength
W = m x g
What is terminal velocity?
Terminal velocity is the maximum speed an object reaches.
Terminal velocity is when the frictional
force on an object is equal to the
driving force. The resultant force is
zero, so it’s acceleration is zero
What is the relationship between
thinking distance, braking distance
and stopping distance?
Stopping distance = thinking distance + braking distance
What factors affect thinking
distance and braking distance?
Thinking distance:
-Tiredness
- Alcohol
- Drugs
Breaking distance:
-Weather
- Road surface
- Condition of brakes
