Forces Quiz

Newton’s First Law of Motion

An object remains at rest or moves at a constant velocity unless acted upon by a net force.

Newton’s Second Law of Motion

The net force acting on an object is equal to the mass of the object multiplied by its acceleration (Fnet = ma).

Newton’s Third Law of Motion

For every action, there is an equal and opposite reaction.

Weight (Force of Gravity)

The force exerted by gravity on an object, calculated as Fg = mg, where m is mass and g is the acceleration due to gravity (9.8 m/s²).

Coefficient of Friction (μ)

A dimensionless scalar value that represents the frictional force between two objects.

Normal Force (N) on a flat surface

The support force that counters the weight of an object resting on a flat surface, calculated as N = mg.

Normal Force (N) on an incline

On an incline, the normal force is calculated as N = mg cos(θ).

Forces on an Incline - Parallel Force (F∥)

The component of gravitational force acting parallel to the incline, calculated as F∥ = mg sin(θ).

Forces on an Incline - Perpendicular Force (F⊥)

The component of gravitational force acting perpendicular to the incline, calculated as F⊥ = mg cos(θ).

Tension (T) when at rest or constant speed

The force in a rope or cable when an object is at rest or moving vertically at constant speed, calculated as T = mg.

Tension (T) when accelerating upward

The tension force must overcome both the weight and the acceleration, calculated as T = mg + ma.

Tension (T) when accelerating downward

The tension force is less than the weight when accelerating downward, calculated as T = mg - ma.

Components of a Force at an Angle - Horizontal (Fx)

The horizontal component of force calculated as Fx = F cos(θ).

Components of a Force at an Angle - Vertical (Fy)

The vertical component of force calculated as Fy = F sin(θ).

Kinematic Equation for Final Velocity (v)

The equation relating initial velocity, acceleration, and time: v = v0 + at.

Kinematic Equation for Displacement (d)

The equation relating initial velocity, time, and acceleration: d = v0t + 1/2 at².

Kinematic Equation relating Final Velocity and Displacement (v²)

The equation relating final velocity, initial velocity, acceleration, and displacement: v² = v0² + 2ad.

Constant velocity implies what about net force?

Net force equals 0 (forces are balanced).

What happens when there is acceleration?

Net force does not equal 0 (use Fnet = ma).

Effect of pulling upward at an angle on normal force

Normal force decreases.

Effect of pushing downward on normal force

Normal force increases.

Friction's role in motion

Friction always opposes motion.

Gravity's effect on an incline

Gravity pulls the object down the ramp, not straight down.