What two things does a force arrow show?
- The length of the arrow shows the size of the force.
- The direction of the arrow shows the direction of the force.
Give some examples of non-contact forces
- Gravitational force
- Electrostatic force
- Magnetic force
What is a ‘resultant force’?
The sum of all forces acting on an object
(the overall force acting on an object)
What equation links force, spring constant and extension?
Force = spring constant x extension
F = k e
Give some examples of contact forces
- Air resistance
- Normal contact force
What are the units for:
a) gravitational field strength
What is the equation that links work done, force and distance?
Work done = force x distance
W = F s
What equation links weight, mass and gravitational field strength?
Weight = mass x gravitational field strength
W = m g
Why type of energy is stored in a spring that is stretched or compressed?
Elastic potential energy
What happens to the temperature of an object experiencing friction?
What is the name of an object that:
a) will return to its original shape after being deformed
b) will not return to its original shape after being deformed
What is the relationship between force and extension of an elastic object?
What happens to air resistance as speed increases?
As speed increases, air resistance increases.
What are typical speed values for someone walking, running and cycling (m/s)?
- Walking 1.5 m/s
- Running 3 m/s
- Cycling 6 m/s
What is the speed of sound?
How many forces need to to be applied to this spring to stretch or compress it?
Two forces (e.g. one at either end)
What equation links acceleration, final velocity, initial velocity and time?
What equation links distance travelled, speed and time?
Distance travelled = speed x time
s = v t
Why does a falling object reach terminal velocity?
- The resultant force on the object is zero.
- Forces of weight and air resistance are balanced.
Name the point on the graph labelled ‘X’
Limit of proportionality
Describe the motion in the following distance-time graph at points a, b, c and d.
a) constant speed
If you wanted to investigate how mass affects acceleration, what part of the equipment would you change?
The mass of the trolley (by adding more masses to the trolley).
Which part of the equipment measures acceleration?
If you wanted to investigate how force affects acceleration, what part of the equipment would you change?
The force pulling the trolley (by adding more masses to the hook).
What is the equation for Newton’s Second Law that links force, mass and acceleration?
Force = mass x acceleration
F = m a
Give three factors that can affect braking distance.
- Road conditions
- Weather conditions: wet / icy roads
- Vehicle conditions: condition of brakes / tyre tread depth
What equation links momentum, mass and velocity?
Momentum = mass x velocity
p = m v
What happens if a car undergoes a large deceleration?
Brakes overheating / loss of control
Describe the motion of a moving car experiencing balanced forces.
Keep moving at a constant speed
Describe the motion of a moving car experiencing unbalanced forces.
The car will change speed (either accelerate or decelerate)