Newton’s second law

• What is the equation for Newton's second law of motion?

  $F =$$m \cdot a$
• What does the resultant force cause according to Newton's laws of motion?

  It causes acceleration
• What is weight caused by?

  It is caused by the gravitational effect of a planet attracting an object’s mass
• How is force (F) measured in Newton's second law?

  In newtons (N)
• How is mass (m) measured in Newton's second law?

  In kilograms (kg)
• How is acceleration (α) measured in Newton's second law?

  In metres per second squared (m/s²)
• How does acceleration relate to resultant force and mass?

  Acceleration is proportional to the resultant force and inversely proportional to the mass
• What does inertial mass measure?

  It measures how difficult it is to change the velocity of an object
• Calculate the force needed to accelerate a 22 kg cheetah at 15 m/s².

  $F =$$22 \times 15 =$$330 \, N$
• What is the force needed to accelerate a 15 kg gazelle at 10 m/s²?

  $F =$$15 \times 10 =$$150 \, N$
• Why is it important to estimate speeds, accelerations, and forces in road vehicles?

  It helps in understanding vehicle performance and safety
• What symbol is used to indicate an approximate value?

  ~ (tilde)
• What are the maximum legal speeds, masses, and accelerations for a family car and a lorry?

  • Family car:
  • Maximum speed: ~27 m/s
  • Mass: ~1,600 kg
  • Acceleration: ~3 m/s²
  • Lorry:
  • Maximum speed: ~22 m/s
  • Mass: ~36,000 kg
  • Acceleration: ~0.4 m/s²
• Estimate the force needed to accelerate a family car to its top speed on a single carriageway.

  $F =$$1,600 \times 3 =$$~4,800 \, N$
• Estimate the force needed to accelerate a lorry to its top speed on a single carriageway.

  $F =$$36,000 \times 0.4 =$$~14,400 \, N$
• What are the key concepts of Newton's second law of motion?

  • Resultant force causes acceleration
  • Weight is due to gravitational attraction
  • Force, mass, and acceleration relationship: \( F = m \cdot a \)
  • Inertial mass measures resistance to velocity change