Honors Physics 9 Final Study Guide — Complete Answers

What is acceleration?

Acceleration is the rate at which velocity changes over time. Unit: m/s².

What is velocity?

Velocity is speed with a direction. Unit: m/s.

What is momentum?

Momentum is mass times velocity: p = m × v. Unit: kg·m/s.

What is energy?

Energy is the ability to do work. Unit: Joules (J).

What is the law of conservation of energy?

Energy cannot be created or destroyed, only transformed.

What are Newton’s Three Laws of Motion?

1st: Objects keep their motion unless acted on by force. 2nd: F = m × a. 3rd: Every action has equal and opposite reaction.

What is a vector? What is a scalar?

Vectors have magnitude and direction. Scalars have only magnitude.

Give examples of vectors and scalars.

Vectors: velocity, force, momentum. Scalars: speed, distance, mass.

What is the Pythagorean Theorem?

c² = a² + b² for right triangles.

What are the free fall equations?

v = v₀ + gt; d = v₀t + (1/2)gt²; v² = v₀² + 2gd.

What is kilo, centi, milli, and micro in metric prefixes?

kilo (k) = 1,000; centi (c) = 0.01; milli (m) = 0.001; micro (μ) = 0.000001.

What is the interaction between two objects according to Newton’s 3rd Law?

Two objects exert forces on each other at the same time.

What is Newton’s 3rd Law?

Every action force has an equal and opposite reaction force.

What is a force pair?

Two forces equal in size and opposite in direction acting on different objects.

What are the four conditions for force pairs?

1. Act on two different objects; 2. Equal magnitude; 3. Opposite direction; 4. Happen simultaneously.

What is a system in science?

Group of interacting objects (e.g., cannon and cannonball).

How does the cannonball and cannon accelerate differently?

Cannonball has smaller mass → larger acceleration; cannon has larger mass → smaller acceleration.

How do you add vectors?

Add components or use tip-to-tail method.

What is a resultant vector?

Single vector that replaces multiple vectors.

How do you calculate a resultant vector?

Use Pythagorean Theorem: R = √(Vx² + Vy²).

What are vector components?

Parts of a vector along x and y axes.

How do you calculate vector components?

Vx = V cos θ; Vy = V sin θ.

What is momentum?

Mass times velocity, p = m × v.

What is the formula for momentum?

p = mv.

What is impulse?

Change in momentum.

What is the impulse formula?

J = F × Δt.

What is the impulse-momentum theorem?

Impulse equals change in momentum, J = Δp.

What is the common form of impulse?

FΔt = mΔv.

How does a boxer riding with a punch work?

Increases impact time, reduces force.

What is the bouncing effect on impulse?

Bouncing increases impulse because momentum change is larger.

What is the bouncing effect on momentum change?

Momentum change doubles when bouncing.

What is the law of conservation of momentum?

Total momentum before collision equals total momentum after.

What happens to momentum in collisions?

Momentum is always conserved.

What is an elastic collision?

Objects bounce off without loss of kinetic energy.

What is the formula for an elastic collision?

Momentum and kinetic energy both conserved.

What is an inelastic collision?

Objects stick together, kinetic energy not conserved.

What is the formula for an inelastic collision?

Use conservation of momentum only.

What happens in a non-head-on collision?

Momentum still conserved in all directions.

What is work?

Force applied times displacement in direction of force.

Why does carrying a 50 lb weight do no work?

No displacement in direction of force (holding still).

What is the work formula?

W = F × d × cos θ.

What is power?

Rate of doing work.

What is the power formula?

P = W/t.

What is mechanical energy?

Sum of kinetic and potential energy.

What is potential energy?

Stored energy due to position.

What is kinetic energy?

Energy due to motion.

What are the energy formulas for potential and kinetic energy?

PE = mgh; KE = (1/2)mv².

What is the energy formula for mechanical energy?

ME = PE + KE.

What is rollercoaster energy at the lowest and highest points?

Max KE at lowest point, max PE at highest point.

Is energy conserved on a rollercoaster?

Mechanical energy (if no friction).

What is efficiency?

Ratio of useful output energy to input energy.

What is the efficiency formula?

Efficiency = (useful energy output / total energy input) × 100%.

What is tangential speed?

Speed along the edge of a rotating object.

What is rotational speed?

Number of rotations per unit time.

What is the relation of tangential to rotational speed?

Tangential speed = radius × rotational speed.

What is rotational inertia?

Resistance to change in rotation; depends on mass distribution.

What is torque?

Rotational equivalent of force.

What is the torque formula?

τ = r × F × sin θ.

What is the center of mass?

Average position of mass in an object.

What is the center of gravity?

Point where gravity appears to act.

What is a rotation point?

Objects rotate about their axis or pivot point.

Is the center of mass always fixed?

Not always; it can move.

Can the center of mass be inside the object?

Not necessarily; can be outside.

What determines stability?

Position of center of mass relative to base.

What is centripetal force?

Force that keeps an object moving in a circle, directed inward.

What is the formula for centripetal force?

Fc = mv²/r.

What is centrifugal force?

Apparent force pushing outward in a rotating frame (not a real force).

When does centrifugal force exist?

Only in rotating (non-inertial) reference frames.

What is the difference between linear and angular momentum?

Linear momentum is straight-line motion; angular momentum is rotational.

What are the angular momentum formulas?

L = Iω (moment of inertia × angular velocity); L = mvr (mass × tangential velocity × radius).

What is the conservation of angular momentum?

Angular momentum stays constant if no external torque acts.