Corrections Flashcards
This is the formula for Kinetic Energy:
E = 1/2mv
True or False?
False. The equation for Kinetic Energy is E = 1/2mv^2
What’s wrong with this equation:
KE = mv^2
The mass is not divided by 2.
It should be KE = 1/2mv^2
List 4 factors decreasing road accidents
- seat belts
- airbags
- safer cars
- crumple zones, or;
- side-impact bars
Seat belts prevent the…
Driver from hitting the steering wheel or windscreen
How do you find the torque of a couple?
One of the forces times the PERPENDICULAR distance between the forces
Why does strain have no unit?
It’s a ratio of two lengths
When acceleration is constant…
Use the constant acceleration equations
Define Ultimate Tensile Strength
Ultimate Tensile Strength is the breaking stress for material
Force F acts on an object at angle Θ, an equation for this is W = FxCosΘ. Why not just W = Fx?
The COMPONENT of the force in the direction of the force is FCosΘ
Force F acts on an object at angle Θ, give an equation for the work done, W
W = FxCosΘ
What does the gradient of a displacement time graph represent?
Velocity
A couple…
Is a pair of equal and parallel but opposite forces
What is Young Modulus defined as?
Stress per strain, as long as elastic limit isn’t reached
Define velocity
Velocity is the rate of change of displacement
What are the conditions for equilibrium?
- all forces on the object equal zero
* net moment about any point is zero
Seat belts decrease…
The impact force on the driver
Airbags deflate…
Quickly to prevent whiplash
What is a Brittle material?
A Brittle material breaks at its elastic limit, it has no plastic region
Couples tend to produce…
Rotation
Define the Joule
The work done when a force of 1N moves 1m in the direction of the net force
What is the equation for Kinetic Energy?
KE = 1/2mv^2
Other than deflating quickly to prevent whiplash, what other safety feature do Airbags feature?
Much wider area of bag reduces the pressure
What is the constant acceleration equation without s?
v = u + at
What is the constant acceleration equation without a?
s = (u+v)/2 x t
What is the constant acceleration equation without v?
s = ut + 1/2at^2
What is the constant acceleration equation without u?
s = vt - 1/2at^2
What is the constant acceleration equation without t?
v^2 = u^2 + 2as
An object travels two paths, one with and one without a slope, both have the same resistive force. Which will travel the furthest?
Journey down the slope, as there is a component of weight acting down. The net force is less, deceleration is smaller.
What type of waves do satellite’s use?
Radio or Microwave
How do you determine the distance between a GPS device and satellite?
Delay time x c
What do satellites use to locate GPS devices?
Trilateration, using spheres
What is delay time?
The time taken for a signal to travel from the satellite to a receiving GPS device
What is the relationship between drag and speed?
Drag is proportional to speed^2
How to do you find stress?
force/area
How do you find strain?
Length/extension
What is the relationship between Young Modulus, strain and stress?
Young modulus = stress/strain
What is Young Modulus measured in?
Pascals (Pa/Nm^-2)
True or false: Kinetic energy is converted into heat energy
True
True or false: gravitational potential energy is converted into heat energy/loss
False. GPE is converted to KE, then KE is converted to heat energy/loss
Define work done
Force by distance moved in the direction of the force
What does a straight gradient on a distance/time graph represent?
Constant speed
True or false: Kinetic energy is converted into heat energy
True
True or false: gravitational potential energy is converted into heat energy/loss
False. GPE is converted to KE, then KE is converted to heat energy/loss
Define work done
Force by distance moved in the direction of the force
What does a straight gradient on a distance/time graph represent?
Constant speed
