Forces and Motion

• What unit is used to measure forces?

  Newton
• What are the two types of forces?

  • Contact forces: act when two surfaces are in contact (e.g., friction, air resistance, tension, normal contact force).
  • Non-contact forces: act over distance (e.g., gravitational attraction, electrostatic force, magnetic force).
• What is a vector?

  A vector is a quantity that has both size and direction.
• How can forces be represented visually?

  Forces can be represented with arrows where the length indicates size and the direction indicates direction.
• What is the difference between mass and weight?

  Weight is a force caused by the mass of an object in a gravitational field.
• In what units is weight measured?

  Newtons
• In what units is mass measured?

  Kilograms
• What is the gravitational field strength on Earth?


  Approximately $9.8 \text{ N/kg}$
• How do you convert mass in kilograms to weight in Newtons?

  Multiply the mass by $9.8 \text{ N/kg}$.
• What instrument is used to measure weight?

  Newton meter
• What instrument is used to measure mass?

  Mass balance
• Where does the weight of an object act?

  At the centre of mass of the object.
• What is the resultant force?

  • The overall force acting on an object.
  • Can be found by combining multiple forces acting in different directions.
• If a 5 Newton force acts to the left and a 10 Newton force acts to the right, what is the resultant force?

  5 Newton force acting to the right.
• What is a balanced force situation?

  • When the overall forces acting on an object are equal and opposite.
  • The object remains stationary or moves at a constant velocity.
• What is the normal contact force?

  The force exerted by a surface to support the weight of an object resting on it.
• How can forces be resolved into components?

  • A force can be broken down into vertical and horizontal components.
  • This helps in analyzing the overall effect of forces acting at angles.
• What is work done on an object?

  Work done is when a force is applied to an object over a distance.
• What is the formula for work done?


  $W =$$F \times d$
• In what units is work done measured?

  Joules
• What is one Joule defined as?

  One Joule is the work done when a force of one Newton causes a displacement of one meter.
• What is elasticity in materials?

  • Elastic materials return to their original shape after the force is removed.
  • Inelastic materials do not return to their original shape after deformation.
• What does the equation $F =$$k \times e$ represent?


  It represents that the force applied is proportional to the extension of the spring.
• What is the unit of spring stiffness?

  Newtons per meter
• What is the formula for elastic potential energy stored in a spring?


  $E =$$\frac{1}{2} k e^2$
• In what units is elastic potential energy measured?


  Joules
• What is the moment of a force?

  The moment is the turning effect of a force, calculated as the force multiplied by the perpendicular distance from the pivot.
• What is the formula for calculating moment?


  $M =$$F \times d$
• What are the units for moment?

  Newton meters
• What is the condition for an object to be in equilibrium?

  • The clockwise moments are equal to the anti-clockwise moments.
  • The object does not rotate.
• What is pressure in fluids?

  Pressure is the amount of force per unit area exerted by a fluid.
• What are the units for pressure?

  Newtons per square meter (Pascals)
• What is the formula for calculating pressure?

  $P =$$\frac{F}{A}$
• How does pressure change with depth in a fluid?

  Pressure increases with depth due to the weight of the fluid above.
• What factors affect pressure in a fluid?

  Pressure depends on the density of the fluid, gravitational field strength, and height.
• What is the formula for pressure in a column of liquid?

  $P =$$\rho g h$
• What is upthrust or buoyancy?


  Upthrust is the upward force acting on an object submerged in a fluid due to pressure differences.
• How does atmospheric pressure change with altitude?

  • Atmospheric pressure decreases with increasing altitude.
  • This is due to fewer air particles impacting the surface at higher elevations.
• What is the relationship between speed and scalar quantities?

  Speed is a scalar quantity that measures how quickly something is traveling.
• What is the speed of sound?

  Approximately 330 meters per second.