Grade 10 Science

Read aloud: v equals d over t. v is the speed, d the distance, t the time — and a formula you can SAY is a formula you own, so say it now (quietly is fine, nobody's looking).

The working habit that earns full marks, here and in every science course after this one: set up before you solve.

Sometimes the speed is the given and the distance is the mystery. One formula, turned around: d = vt — read aloud, d equals v t.

Every “are we there yet” ever asked is this formula, waiting to be written down. Run the units check again: m over m/s — the metres cancel and seconds remain.

Physics thinks in m/s; the road signs outside think in km/h.

Real trips change pace — highway, roadwork, back roads.

And here is the wonderful part: light plays by the same rule.

But push light INTO glass or water and it genuinely slows down.

A straw in a glass of water looks broken at the surface because light changes direction the instant it changes speed.

Light leaving water for air bends AWAY from the normal — the exit angle is always wider than the angle inside.

A concave mirror is a polished slice of a sphere, and that sphere has a radius R — the radius of curvature. Shine parallel rays at the mirror (sunlight does nicely) and they all bounce through one bright point: the focus.

It is this chapter's first full ladder: pick the formula, rearrange it, place the givens, then compute. The one rule of reciprocal land: never add the plain distances.

Magnification answers the honest question: how many times bigger is the image than the thing itself?

A SHORT focal length means a strong lens that bends light hard, so flipping f makes bigger mean stronger — which is exactly how a label should behave.

Dip a spoon in your hot chocolate and dip a spoon in a hot bath. The hot chocolate is hotter — but the bath could melt a whole snowman, and the mug could not.

Warming things up costs energy, and every material posts its price: the specific heat capacity c, in joules per kilogram per degree.

Detectives with thermometers. Your safety rail when rearranging is the units. Whatever you solve for, push the units through: if they refuse to cancel down to the answer's units, the rearrangement is wrong — no appeal.

Drop a thermometer into a glass of melting ice and watch closely: heat pours in from the warm room, and the reading parks at 0 °C until the last sliver of ice is gone.

The rule is simply to price every leg and add them. Ice from the deep freeze climbs to 0 °C, crosses the melting plateau, and climbs again as water — three legs, three lines, one total.

Warm a solid and it grows — every metre of it, by a tiny fixed fraction, for every degree.

So far every answer has been a lump sum of joules. But heat through a window never finishes — it runs as a steady rate, joules every second, and a joule per second has a name you know from light bulbs: the watt.

Electricity is stuff on the move. The stuff is charge, measured in coulombs (C) — one coulomb is about six billion billion electrons, a crowd far too big to count one by one.

Meet the most famous formula in electricity: V = IR — read aloud: V equals I R. V is voltage in volts, the push. I is current in amperes, the flow. R is resistance in ohms (Ω — the Greek letter omega), how much the path squeezes.

V = IR is one fact in three outfits.

Put two resistors end to end — a single loop, no branches — and you have a series circuit. The same current threads through both, like one line of people passing through two doorways.

Now give the current a choice: two resistors side by side, each on its own branch, make a parallel circuit. More paths make the trip EASIER, so the total resistance drops below the smallest branch — always.

Power is how fast a device spends energy, measured in watts (W) — one watt is one joule spent per second. The main road: P = VI — read aloud: P equals V I — the push times the flow.

Your hydro bill never mentions joules — the joule is too small a coin for a month of electricity. The bill's unit is the kilowatt-hour (kWh): what a 1000 W device spends in one hour of running.

The unit is the pascal: one newton spread over one square metre. A pascal is tiny — a single sheet of paper lying flat presses on the table with about 1 Pa.

Here is the nugget that ties the chapter together: ten metres of water costs about 98 kPa — almost exactly one whole atmosphere.

You live at the bottom of an ocean of air. At sea level it presses with about 100 kPa — the weight of everything overhead.

Air holds water as invisible vapour, and how much it CAN hold depends on temperature: warm air is a bigger sponge.

Take today's air, with today's water in it, and COOL it. The sponge shrinks around the same water, RH climbs, and at some exact temperature it hits 100 %.

The thermometer reports the air; your skin reports the EXPERIENCE, and two things drive them apart. In summer, moisture: sweat cools you by evaporating, and near-full air won't take the water, so heat piles up.

The scores tell a climate story in one line: fresh snow reflects about 0.9 of its sunlight; grass about 0.25; open water a mere 0.06.

Lightning hands you a free measuring tape. The flash reaches your eyes essentially instantly; the thunder plods along at the speed of sound, so the count between them IS the distance, in disguise.