The inclined plane, a simple ramp, is one of the classic setups in physics, and it is the perfect place to see how forces combine, so this calculator resolves the whole problem for you the moment you enter the numbers. Give it the slope angle, the mass of the object, and optionally a coefficient of friction, and it returns the force pulling the object down the slope, the force pressing into the slope, the normal force from the surface, the friction force and the resulting acceleration, all updating as you type. The key idea is that gravity always pulls straight down, but on a slope it is far more useful to split that pull into two directions: one running along the slope, which is the weight times the sine of the angle and tends to slide the object downhill, and one pressing into the slope, the weight times the cosine of the angle, which the surface resists with an equal and opposite normal force. Friction then enters as the coefficient of friction times that normal force, always opposing motion, so the net force down the slope is the gravity component minus the friction. Divide by the mass and you have the acceleration, which the calculator gives as zero when friction is strong enough to hold the object still. Seeing all these pieces at once, and watching them shift as you steepen the slope or add friction, makes the geometry of forces genuinely click. That makes the tool especially useful for senior school and university physics students learning to resolve forces and checking homework, and for anyone working with ramps, chutes, conveyors or loading slopes in the real world. It uses g of 9.81 metres per second squared. The formulas and a worked example are explained clearly below.
Forces in newtons, using g = 9.81 m/s². If friction holds the object still, the acceleration is shown as 0.
With weight W = m g: the component along the slope is W times the sine of the angle; the normal force is W times the cosine of the angle. The maximum friction is the coefficient of friction times the normal force. The net force down the slope is the along-slope component minus friction (not below zero), and the acceleration is the net force divided by the mass, which equals g times (sine minus the coefficient times cosine).
For a 30 degree slope, a 10 kg mass and friction 0.2: the along-slope force is 10 times 9.81 times sin 30, about 49.1 N. The normal force is 10 times 9.81 times cos 30, about 85.0 N, so friction is about 17.0 N. The net force is about 32.1 N and the acceleration about 3.21 m/s².
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