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🎓 Physics Equations: Interactive Lesson on Key Physics Formulas

Practice applying important physics equations involving motion, force, energy, and electricity.

This entry is part 1 of 63 in the series Science
Physics Equations: Interactive Lesson on Key Physics Formulas.
Practice applying important physics equations involving motion, force, energy, and electricity.

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Physics Equations: Interactive Lesson on Key Physics Formulas

Practice applying important physics equations involving motion, force, energy, and electricity. This comprehensive quiz covers: Newton's second law (F = ma, 2,000 N for 1,000 kg at 2 m/s²), weight (W = mg, 98 N for 10 kg), kinetic energy (KE = ½mv², 9 J for 2 kg at 3 m/s), gravitational potential energy (PE = mgh, 98 J for 5 kg at 2 m), work (W = Fd, 150 J for 50 N over 3 m), power (P = W/t, 200 W for 1,000 J in 5 s), Ohm's law (V = IR, 20 V for 2 A through 10 Ω), electric power (P = IV, 240 W for 2 A at 120 V), density (ρ = m/V, 5 g/cm³ for 50 g in 10 cm³), and Einstein's mass-energy equivalence (E = mc², 9 × 10¹⁶ J for 1 kg). Perfect for grades 9-12.

F = ma = (1,000 kg) × (2 m/s²) = 2,000 N. The unit of force is the newton (N). One newton is the force required to accelerate 1 kg at 1 m/s².

Newton's second law of motion states that the net force acting on an object is equal to the product of its mass and acceleration: F = ma. Force is measured in newtons (N), mass in kilograms (kg), and acceleration in meters per second squared (m/s²). A 1,000 kg car accelerates at 2 m/s². What net force is required?

W = mg = (10 kg) × (9.8 m/s²) = 98 N. On the Moon (g = 1.6 m/s²), the weight would be 16 N. The mass remains 10 kg.

Weight is the force of gravity on an object. The formula is W = mg, where m is mass (kg) and g is acceleration due to gravity (9.8 m/s² on Earth). What is the weight of a 10 kg object on Earth?

KE = ½ × (2 kg) × (3 m/s)² = ½ × 2 × 9 = 9 J. Kinetic energy increases with the square of velocity (doubling velocity quadruples KE).

Kinetic energy is the energy of motion. The formula is KE = ½mv², where m is mass (kg) and v is velocity (m/s). The unit is the joule (J). A 2 kg object moving at 3 m/s has how much kinetic energy?

PE = mgh = (5 kg) × (9.8 m/s²) × (2 m) = 98 J. The object gains 98 J of potential energy. If dropped, it would convert to kinetic energy.

Gravitational potential energy is stored energy due to height. The formula is PE = mgh, where m is mass (kg), g is gravity (9.8 m/s²), and h is height (m). A 5 kg object is lifted 2 meters. How much potential energy does it gain?

W = Fd = (50 N) × (3 m) = 150 J. If the force is at an angle, use W = Fd cosθ. No work is done if the object does not move (d = 0).

Work is done when a force causes displacement. The formula is W = Fd (force × distance), where force is in the direction of motion. The unit is the joule (J). A force of 50 N pushes a box 3 meters across the floor. How much work is done?

P = W/t = 1,000 J / 5 s = 200 W. Horsepower (hp) is another unit: 1 hp = 746 W. A typical car engine has about 150-300 hp.

Power is the rate at which work is done or energy is transferred. The formula is P = W/t (work/time) or P = ΔE/t. The unit is the watt (W). 1 W = 1 J/s. A motor does 1,000 J of work in 5 seconds. What is its power output?

V = IR = (2 A) × (10 Ω) = 20 V. Ohm's law is fundamental to electrical engineering. Resistors obey Ohm's law; diodes and transistors do not (non-ohmic).

Ohm's law states that the voltage (V) across a resistor is equal to the current (I) times the resistance (R): V = IR. Voltage is measured in volts (V), current in amperes (A), and resistance in ohms (Ω). A circuit has a resistance of 10 Ω and a current of 2 A. What is the voltage?

P = IV = (2 A) × (120 V) = 240 W. Power is measured in watts (W). A kilowatt (kW) is 1,000 W. Energy (kWh) = power × time.

Electric power is the rate at which electrical energy is transferred. The formula is P = IV (power = current × voltage). Also P = I²R = V²/R. A device draws 2 A of current at 120 V. What is its power?

ρ = m/V = 50 g / 10 cm³ = 5 g/cm³. If density is less than water (1 g/cm³), the object floats. If greater, it sinks.

Density is mass per unit volume. The formula is ρ = m/V (rho = mass/volume). The SI unit is kg/m³. Common units: g/cm³ (for solids/liquids). Water density is 1 g/cm³ (1,000 kg/m³). An object has a mass of 50 g and a volume of 10 cm³. What is its density?

E = mc² = (1 kg) × (3 × 10⁸ m/s)² = 9 × 10¹⁶ J. This is equivalent to about 21 megatons of TNT (much more than the atomic bombs dropped on Japan).

Einstein's mass-energy equivalence formula is E = mc², where E is energy (joules), m is mass (kg), and c is the speed of light (about 3 × 10⁸ m/s). This equation shows that mass can be converted into enormous amounts of energy (nuclear power, atomic bombs). How much energy is released from 1 kg of mass converted entirely to energy?

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Welcome to our Science Lessons and Quiz series! Each lesson combines learning and assessment through 10 carefully crafted questions. The questions introduce key scientific concepts, while the detailed explanations following each answer help learners verify their understanding and deepen their knowledge. Explore biology, chemistry, physics, earth science, and more through an engaging, interactive learning experience.

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⚛️ Fun fact: Einstein\’s famous equation E = mc² is not just for nuclear bombs and power plants. It also explains how the Sun produces energy. In the Sun\’s core, about 600 million tons of hydrogen fuse into helium every second, converting about 4 million tons of matter into energy (E = mc²). This energy powers the Sun and provides the light and heat that support life on Earth. The equation also explains why the Sun will eventually run out of fuel (after about 5 billion more years). Without E = mc², we would not understand nuclear fusion, the source of energy for stars.

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