Grade 10 physics – Introduction to Physics Quiz

Physics is the branch of science that investigates matter, energy, forces and how they interact, which explains natural phenomena from motion to heat.

The metre is the SI base unit for length and is used in Kenya schools and laboratories for measuring distances.

A beam balance compares an object's mass with standard masses and gives a direct measure of mass; a spring balance measures weight (force).

Mass is the quantity of matter (kg) while weight is the force of gravity on that mass (N = mass × gravitational acceleration).

Displacement has both magnitude and direction, which makes it a vector; speed, mass and time are scalars (no direction).

Average speed is total distance travelled divided by the time taken. Displacement/time gives average velocity, which includes direction.

The newton (N) is the SI unit of force. One newton is the force that gives a 1 kg mass an acceleration of 1 m/s².

Newton's first law says objects keep their state of motion unless a net external force acts on them; this is the principle of inertia.

Acceleration is change in velocity (which includes direction) per unit time. It can be due to speed change or direction change.

Friction arises because surfaces have tiny irregularities that catch and resist relative motion; it is not due to colour or magnetism in ordinary cases.

Work = force × displacement in the direction of the force. If there is no displacement in the force direction, no work is done.

The joule (J) is the SI unit of energy and work. One joule is one newton of force causing one metre of displacement.

The total energy in a closed system remains constant; it simply changes form (e.g., kinetic to thermal) but is not lost.

Heat is energy flow from hotter to colder bodies. Temperature indicates the average kinetic energy of particles (how hot/cold an object is).

Kelvin temperature ≈ Celsius + 273 (more precisely +273.15). Kenyan school problems commonly use +273 for conversions.

Specific heat capacity is the amount of heat energy needed to raise one kilogram of a substance by one degree Celsius (or Kelvin).

Gases expand much more than liquids or solids for a given temperature rise because their molecules are far apart and move more freely.

Radiation transfers heat by electromagnetic waves and does not require matter (so it works through vacuum); conduction and convection need material media.

Latent heat of fusion is the energy absorbed per kilogram to melt a solid into a liquid without change in temperature.

Pressure is the force applied per unit area on a surface. Its SI unit is the pascal (N/m²).

Density is mass per unit volume (kg/m³). It determines whether objects float or sink in a fluid of known density.

Floating occurs when the upward buoyant force (equal to weight of fluid displaced) balances the object's weight, giving equilibrium.

A lever is a rigid bar pivoted at a fulcrum; it amplifies force depending on distances from the pivot (used in seesaws, crowbars).

Power is the rate of doing work; it equals the work done divided by the time taken. Its SI unit is the watt (J/s).

Thermal equilibrium means no net heat transfer between objects because they share the same temperature; this is the basis of the zeroth law of thermodynamics.