forces in action

• What is the relationship between resultant force, mass, and acceleration?

  The resultant force is related to mass and acceleration by the formula $F =$$ma$.
• What is the SI unit for force?

  The SI unit for force is kgms^-2.
• How is one Newton defined?

  One Newton is defined as the force that will give a mass of 1 kg an acceleration of 1 ms^-2.
• What is the weight of an object?

  The weight of an object is defined as the gravitational force acting upon the object.
• How do you determine the weight of an object?

  You can determine the weight of an object using the formula $W =$$mg$, where $g$ is the acceleration of free fall.
• How does the weight of an object change when taken to another location?

  The weight of an object will change if it is taken to another location where the acceleration of free fall is different.
• What is the formula for weight?

  The formula for weight is $W =$$mg$.
• What are the commonly occurring forces?

  • Weight: gravitational force acting on an object
  • Friction: force arising when two surfaces rub against each other
  • Drag: resistive force on an object travelling through a fluid
  • Tension: force within a stretched cable or rope
  • Up-thrust: upward buoyancy force in a fluid
  • Normal Contact Force: force acting at a 90° angle to the plane of contact
• What are free-body diagrams used for?

  Free-body diagrams are used to model all of the forces acting on an object.
• How are forces represented in free-body diagrams?

  Each force is represented as a vector arrow, scaled to the magnitude of the force and pointing in the direction it acts.
• What can free-body diagrams help identify?

  Free-body diagrams can help identify which forces act in which plane and resolve the net force in a particular direction.
• How can you resolve forces in free-body diagrams?

  You can resolve each force into its horizontal and vertical components.
• What happens if an object experiences a constant net force?

  If an object experiences a constant net force, there must be a resultant acceleration determined using $F =$$ma$.
• How does motion extend to a 2-D plane?

  Motion can extend to a 2-D plane, such as a slope, where different forces act in different directions.
• What forces act on an object on a slope?

  The weight acts vertically down, friction acts along the slope, and the normal reaction force acts at a 90° angle to the slope.
• Why is it easier to resolve forces acting on a slope into components?

  It is often easier to resolve the forces into components acting parallel and perpendicular to the slope.
• What is drag?

  Drag is a frictional force that opposes motion when an object moves through a fluid.
• What factors affect the magnitude of drag force?

  The magnitude of drag force depends on the speed of the object, shape, texture, and density of the fluid.
• How is drag related to speed?

  Drag is proportional to the square of the speed of the object.
• What happens to drag as the cross-sectional area increases?

  Drag increases as the cross-sectional area of the object increases.
• What is terminal velocity?

  Terminal velocity is reached when the drag force equals the weight of the object, resulting in zero net force and no further acceleration.
• What occurs as the velocity of a falling object increases?

  As the velocity of a falling object increases, the magnitude of the drag force also increases.
• What happens to the net force on an object as drag increases?

  The net force on the object reduces until it is zero as drag increases.
• How can terminal velocity be determined experimentally?

  Terminal velocity can be determined by releasing a ball bearing in a viscous fluid and measuring its distance traveled over time.
• What is the purpose of a pulley system in the terminal velocity experiment?

  A pulley system can increase the accuracy of the terminal velocity experiment by allowing precise measurement of the ball bearing's speed.
• What is the moment of a force?

  The moment of a force is defined as the magnitude of the force multiplied by the perpendicular distance from the force to the pivot.
• What is the SI unit for moment of a force?

  The SI unit for moment of a force is Nm.
• How is the distance used in calculating moment defined?

  The distance used is the perpendicular distance between the pivot point and the line of action of the force.
• What happens if the force is acting parallel to the pivot?

  If the force is acting parallel to the pivot, it will not produce a moment.
• What is a couple in physics?

  A couple is a pair of forces that have equal magnitude and opposite direction, applied in parallel along different lines.
• What is torque in relation to a couple?

  The torque of a couple is defined as the product of the magnitude of one of the forces and the perpendicular separation between the forces.
• What is the principle of moments?

  The principle of moments states that for a body in equilibrium, the sum of clockwise moments equals the sum of anti-clockwise moments about any point.
• How can unknown forces or distances be determined using the principle of moments?

  Unknown forces or distances can be determined by resolving all forces into horizontal and vertical components and calculating moments.
• What is the centre of mass of an object?

  The centre of mass is the point where the entire weight of the object appears to act.
• How does the centre of mass relate to motion in a gravitational field?

  The centre of mass is the point through which the application of an external force produces only motion in a straight line, with no rotation.
• How can the centre of mass be determined for a freely suspended object?

  A freely suspended object will come to rest with its centre of mass vertically below its suspension point.
• How can the centre of mass be determined using a plumb line?

  The centre of mass can be determined by suspending the object and drawing lines along the string from a plumb bob to find the intersection point.
• What is the formula for density?

  The formula for density is $\rho =$$\frac{m}{V}$.
• What is the SI unit for density?

  The SI unit for density is kgm^-3.
• How can the density of an object be determined?

  The density can be determined by measuring mass with scales and volume using appropriate methods for the object's state.