P2 - Forces

• What units can distance be measured in?

  Distance can be measured in mm, cm, m, and km.
• What units can time be measured in?

  Time is measured in ms, s, mins, and hours.
• How is speed calculated using distance and time?

  Speed is calculated using the formula: $speed =$$\frac{distance}{time}$.
• What is the difference between a vector and a scalar?

  A vector has magnitude and direction, while a scalar has only magnitude.
• Why can speed be considered a scalar quantity?

  Speed is a scalar because it does not have a direction associated with it.
• What does velocity represent in comparison to speed?

  Velocity is a vector that gives speed in a given direction.
• What do distance-time graphs represent?

  • Time on the x-axis and distance on the y-axis
  • Gradient shows velocity
  • Steeper gradient indicates faster speed
  • Negative gradient indicates returning to the starting point
  • Horizontal line indicates the object is stationary
  • Curved line indicates changing velocity (acceleration or deceleration)
• What do velocity-time graphs represent?

  • Time on the x-axis and velocity on the y-axis
  • Gradient shows acceleration
  • Steeper gradient indicates greater acceleration
  • Negative gradient indicates deceleration
  • Horizontal line indicates constant speed
  • Area under the curve gives total distance travelled
• How is average speed calculated when speed changes during motion?

  Average speed is calculated using the formula: $average\ speed =$$\frac{total\ distance}{total\ time}$.
• What is electrostatic interaction?

  Electrostatic interaction occurs between charged particles, resulting in attraction or repulsion.
• What is gravitational attraction?

  Gravitational attraction occurs between particles with mass.
• What are contact forces?

  Contact forces are experienced in the opposite direction to contact, such as friction.
• What do free body force diagrams show?

  • Direction of forces acting on an object
  • Reaction force acts normal (perpendicular) to the line of contact
  • Friction acts in the opposite direction to movement
  • Weight acts vertically downwards from the object's center of mass
• How do scale drawings represent forces?

  • Length of each arrow represents size of the force
  • Bigger arrow indicates greater force
  • Forces in opposite directions with equal length cancel out (equilibrium)
  • Resultant force shown by the larger arrow
• What does Newton's First Law state?

  An object has a constant velocity unless acted on by a resultant force.
• What happens to a vehicle's acceleration as air resistance increases?

  As air resistance increases, the resultant acceleration from thrust decreases.
• What is Newton's Second Law?

  Newton's Second Law states that the acceleration or deceleration depends on the direction and magnitude of the resultant force.
• What is the formula for force according to Newton's Second Law?

  The formula is $F =$$m \times a$.
• What is inertia?

  Inertia is the measure of how difficult it is to change the velocity of an object depending on its mass.
• How is momentum calculated?

  Momentum is calculated using the formula: $p =$$m \times v$.
• What happens in an elastic collision?

  • Momentum and kinetic energy are conserved
  • Total momentum before collision equals total momentum after
  • Total kinetic energy before collision equals total kinetic energy after
• What is the recoil speed of a gun when a bullet is fired?

  The recoil speed can be calculated using momentum conservation principles.
• What does Newton's Third Law state?

  Every action force has an equal and opposite reaction force.
• How is work done calculated?

  Work done is calculated using the formula: $w =$$F \times d$.
• What is the unit of work done?

  Work done is measured in Joules.
• What is deformation in physics?

  • Changes in shape caused by stretching forces
  • Two main types: elastic and plastic deformation
• What is elastic deformation?

  • The object returns to its original shape when the load is removed
  • Example: an elastic band
• What is plastic deformation?

  • The object does not return to its original shape when the load is removed
  • Example: a spring pulled too far
• What is Hooke's Law?

  Hooke's Law states that $F =$$kx$, where F is the force, k is the spring constant, and x is the extension.
• What does a linear line on a force-extension graph indicate?

  • Indicates elastic deformation
  • Follows Hooke's Law
  • Gradient equals spring constant (k)
• What happens at the elastic limit on a force-extension graph?

  • The trend stops being linear
  • The material does not obey Hooke's Law beyond this point
• What does non-linear behavior on a force-extension graph indicate?

  • Indicates non-elastic behavior
  • The material does not obey Hooke's Law
• How is work done on a spring calculated?

  Work done on a spring can be calculated as the area under the force-extension graph: $W =$$\frac{1}{2} k x^2$.
• What is weight in physics?

  Weight is the force exerted on a mass by the gravitational field, measured in Newtons.
• How does weight change on different planets?

  Weight changes on different planets due to varying gravitational field strengths, while mass remains the same.
• What is the formula for gravitational potential energy?

  The formula is $PE =$$mgh$, where m is mass, g is gravitational field strength, and h is height.
• What is the moment of a force?

  The moment of a force is calculated using the formula: $M =$$F \times d$, where F is the force and d is the perpendicular distance.
• What is equilibrium in terms of moments?

  • An object is in equilibrium when there is no resultant moment
  • Sum of anticlockwise moments equals sum of clockwise moments
• How do gears change speed, force, or direction?

  • Lower gears have fewer teeth and turn faster with less force
  • Higher gears have more teeth and turn slower with greater force
• What does pressure in fluids cause?

  Pressure in fluids causes a net force at right angles to any surface.