Physics Practice Questions
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This document contains a series of physics practice questions focusing on calculations related to heat, electricity, waves, and mechanics. The questions are accompanied by their solutions. The physics problems cover a range of topics, providing valuable practice for students.
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A 2 kg object at 80°C is dropped into 500 g of water at 20°C. If no heat is lost, what is the final temperature? (Specific heat of object = 0.5 J/g°C, specific heat of water = 4.18 J/g°C) Use: m1c1(Tf-T1) = m2c2(T2-Tf) A resistor has a voltage of 240 V and a current of 5 A. What is its resistance?...
A 2 kg object at 80°C is dropped into 500 g of water at 20°C. If no heat is lost, what is the final temperature? (Specific heat of object = 0.5 J/g°C, specific heat of water = 4.18 J/g°C) Use: m1c1(Tf-T1) = m2c2(T2-Tf) A resistor has a voltage of 240 V and a current of 5 A. What is its resistance? Resistance = Voltage / Current = 240 V / 5 A = 48 Ω An electric circuit uses 3 A of current and a 10 Ω resistor. What is the voltage? Voltage = Current \* Resistance = 3 A \* 10 Ω = 30 V A device uses 1,500 W of power at 120 V. What is the current? Current = Power / Voltage = 1500 W / 120 V = 12.5 A A 60 W bulb operates at 120 V. What is its resistance? Resistance = Voltage² / Power = (120 V)² / 60 W = 240 Ω A circuit operates with 5 A of current and a resistance of 20 Ω. What is the power output? Power = Current² \* Resistance = (5 A)² \* 20 Ω = 500 W A 240 V appliance draws 10 A of current. How much energy does it use in 5 hours? Energy = Power \* Time = (240 V \* 10 A) \* (5 h \* 3600 s/h) = 43.2 MJ A light wave takes 10 minutes to travel from the Sun to Earth. How far is Earth from the Sun? Distance = Speed \* Time = (3.0 x 10⁸ m/s) \* (10 \* 60 s) = 1.8 x 10⁹ km A wave has a frequency of 500 Hz and a speed of 340 m/s. What is its wavelength? Wavelength = Speed / Frequency = 340 m/s / 500 Hz = 0.68 m A metal block has a density of 8 g/cm³ and a volume of 50 cm³. What is its mass? Mass = Density \* Volume = 8 g/cm³ \* 50 cm³ = 400 g A person exerts a 250 N force on a 1.5 m² surface. What is the pressure exerted? Pressure = Force / Area = 250 N / 1.5 m² = 166.7 Pa A car of mass 1,000 kg is moving at 20 m/s. What is its kinetic energy? Kinetic Energy = (1/2) \* Mass \* Velocity² = (1/2) \* 1000 kg \* (20 m/s)² = 200,000 J A machine does 3,000 J of work in 5 seconds. What is its power output? Power = Work / Time = 3,000 J / 5 s = 600 W
