Gravity pulls. Your edges decide where.

On a slope at angle θ, your weight mg splits in two: mg sin θ along the slope, pulling you downhill, and mg cos θ into the snow, pressing you onto it. Subtract snow friction (Ch 2) and you get the acceleration: a = g (sin θ − μ cos θ). Slopes are often quoted as a percentage: gradient = tan θ × 100.

Why beginners start on gentle slopes

On a 5° nursery slope, speed builds slowly enough to practise the snow plough. Below about 3° on groomed snow, gravity barely beats friction and you'll hardly move at all: try it in the Slope Lab.

The friction between a waxed base and snow is low, typically quoted around μ ≈ 0.03–0.1. A big reason is frictional melting: rubbing heats the contact points and makes a microscopic water layer that lubricates the base. Very cold, dry snow melts less and feels slow; wet spring snow can feel sticky because water films create suction.

Snow plough to parallel

Beginners brake with the snow plough: tails pushed apart, skis tipped onto their inside edges so they scrape snow sideways. IISM Gulmarg's 14-day basic course syllabus builds from walking and sliding to snow plough, snow plough turns, traversing, uphill swings and side stepping, then basic swings; the intermediate and advanced courses move on to side-slip garlands, downhill swings and parallel turns with open and then closed skis, and slalom.

Air drag is ½ ρ C_d A v²: air density × drag area × speed squared. As you speed up, drag grows until gravity along the slope equals friction plus drag. That's your top (terminal) speed: v_max = √(2 (mg sin θ − μ mg cos θ) ÷ (ρ C_dA)). Unlike acceleration, top speed does depend on mass: heavier skiers go faster when drag matters.

Altitude and drag

Gulmarg's gondola climbs from about 2,650 m to 3,980 m, according to IISM. At 3,980 m the standard atmosphere gives about 61% of sea-level pressure, so the air is thinner and drag a little lower. Racers in a tuck exploit drag; recreational skiers control speed with turns instead (Ch 4).

To follow a curve of radius r at speed v, something must push you sideways with force m v² ÷ r. On skis or a snowboard, that's the snow pushing back on your tilted edge. To balance, you lean into the turn at angle φ with tan φ = v² ÷ (g r).

How turns control speed

• Across the fall line: the steepest line down the hill is the fall line. Ski across it and the slope along your path is far gentler.
• Skidding vs carving: a skidded turn scrapes snow and converts kinetic energy into heat; a carved turn rides the edge cleanly and keeps speed. Beginners skid; experts choose.
• Sidecut: a ski is narrower at the waist than at the tip and tail. Tilt it on edge and it bends into an arc, which is what makes carving possible.
• Snowboarding: the same physics on one board, with heel-side and toe-side edges. ABVIMAS (Solang) and IISM (Gulmarg) both run snowboarding courses.

Kinetic energy is ½ m v²: double your speed and you carry four times the energy into any fall or collision. A helmet, a controlled speed and space between you and others are the main defences.

Slope etiquette is physics too

• The skier below has priority: they can't see you. Give them room.
• Stop where you're visible from above, and look uphill before setting off.
• Ski in control, at a speed where you could stop or avoid someone.

Avalanches

Snow builds up in layers. When a weak layer fails under a stiffer slab, the slab can release and slide. Most slab avalanches start on slopes of roughly 30°–45°, often triggered by the victim or their group. Gulmarg's high terrain above the gondola is serious avalanche country.

Indian ski areas sit high: Auli at around 2,800 m (Uttarakhand Tourism), and Gulmarg from about 2,650 m to 3,980 m at the gondola top (IISM). The International Standard Atmosphere gives the drop in air pressure, and with it the oxygen in every breath.

Staying well

• Altitude: take it easy on day one, drink water, and descend if headache, nausea or breathlessness get worse.
• Cold: IISM notes Gulmarg can drop to −8 °C in winter. Layers, gloves, a hat under the helmet; watch fingers, toes and faces for frostbite.
• Sun: fresh snow reflects most sunlight and thin air filters less UV. Goggles or dark glasses prevent snow blindness; sunscreen on face and lips.