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Quiz Newtonian Mechanics: gravity, momentum, energy, friction

Test your grip on classical physics: Newton's laws, gravity, momentum, kinetic energy and friction. Eleven verified questions with clear explanations.

12 questions~6 minen
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What does Newton's second law state?

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  1. Q1. What does Newton's second law state?

    • F = m + a
    • F = m / a
    • F = m × a
    • F = m − a
    Newton's second law, published in the Principia (1687), says the net force on an object equals its mass times its acceleration. The unit is the newton (N), where 1 N = 1 kg·m/s².

  2. Q2. Approximate value of gravitational acceleration g at Earth's surface?

    • 1.6 m/s²
    • 9.81 m/s²
    • 32 m/s²
    • 100 m/s²
    Standard gravity is 9.80665 m/s², usually rounded to 9.81 m/s². On the Moon it's only about 1.62 m/s², roughly one-sixth of Earth's.

  3. Q3. Which quantity is conserved in an isolated collision (no external force)?

    • Velocity
    • Kinetic energy only
    • Linear momentum
    • Acceleration
    Linear momentum p = m·v is always conserved when no external force acts. Kinetic energy is only fully conserved in elastic collisions; inelastic ones lose some to heat or deformation.

  4. Q4. How is kinetic energy of a moving object calculated?

    • m·v
    • ½·m·v²
    • m·g·h
    • m·v²
    Kinetic energy KE = ½·m·v². A car doubling its speed therefore quadruples its kinetic energy, which is why stopping distances grow so fast with speed.

  5. Q5. Newton's law of universal gravitation says the force between two masses is...

    • Proportional to distance
    • Inversely proportional to distance
    • Inversely proportional to distance squared
    • Independent of distance
    F = G·m₁·m₂ / r². The gravitational constant G ≈ 6.674 × 10⁻¹¹ N·m²/kg² was first measured by Henry Cavendish in 1798 using a torsion balance.

  6. Q6. What does Newton's third law state?

    • Objects fall at the same rate
    • Energy is conserved
    • For every action there is an equal and opposite reaction
    • Force equals mass times acceleration
    When body A pushes B with force F, body B pushes A with −F. That's why a rocket accelerates: hot gases pushed backward push the rocket forward.

  7. Q7. Which scientist showed that all objects fall at the same rate in a vacuum?

    • Aristotle
    • Galileo Galilei
    • Tycho Brahe
    • Robert Hooke
    Galileo argued around 1590 that mass doesn't affect fall rate in vacuum. Apollo 15 astronaut David Scott famously verified it on the Moon in 1971 by dropping a hammer and a feather.

  8. Q8. What is friction?

    • A type of gravity
    • A force that opposes relative motion between surfaces
    • A form of kinetic energy
    • Magnetic attraction
    Friction resists sliding between contacting surfaces. It comes from microscopic roughness and adhesion. Kinetic friction is usually less than static friction, which is why pushing something is hardest at the start.

  9. Q9. Gravitational potential energy near Earth's surface is...

    • m·v²
    • ½·k·x²
    • m·g·h
    • F·d²
    PE = m·g·h, where h is height above a reference level. Lifting a 1 kg book 1 m gains about 9.81 joules of potential energy, which converts to kinetic energy if it falls.

  10. Q10. What is the SI unit of work and energy?

    • Watt
    • Joule
    • Newton
    • Pascal
    The joule (J) equals 1 N·m. James Prescott Joule established the mechanical equivalent of heat in the 1840s, linking mechanical work and thermal energy.

  11. Q11. Why does a satellite stay in orbit instead of falling to Earth?

    • There is no gravity in space
    • It moves sideways fast enough that Earth curves away beneath it
    • Air pressure holds it up
    • Magnetism repels it
    A satellite is constantly falling, but its tangential speed (about 7.8 km/s for low Earth orbit) means Earth's surface curves away just as fast. Newton illustrated this with his famous 'cannonball' thought experiment.

  12. Q12. What does the work-energy theorem state?

    • Work equals mass times gravity
    • The net work on an object equals its change in kinetic energy
    • Work cannot be done in a vacuum
    • Work always becomes heat
    W_net = ΔKE. Push a 2 kg block from rest to 3 m/s and you've done 9 J of net work, regardless of the path taken to get there.

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