Physics Calculations Practice Questions

Find the momentum of a 50 kg object moving at 4 m/s. Momentum = Mass \* Velocity = 50 kg \* 4 m/s = 200 kg·m/s What is the impulse when a 20 N force acts for 5 seconds? Impulse = Force \* Time = 20 N \* 5 s = 100 Ns Find the power required to lift a 100 N weight by 2 meters in 5 seconds. Power...

Find the momentum of a 50 kg object moving at 4 m/s. Momentum = Mass \* Velocity = 50 kg \* 4 m/s = 200 kg·m/s What is the impulse when a 20 N force acts for 5 seconds? Impulse = Force \* Time = 20 N \* 5 s = 100 Ns Find the power required to lift a 100 N weight by 2 meters in 5 seconds. Power = Work / Time = (100 N \* 2 m) / 5 s = 40 W A 2 kg object is moving with 10 m/s speed. Find its kinetic energy. Kinetic Energy = (1/2) \* Mass \* Velocity² = (1/2) \* 2 kg \* (10 m/s)² = 100 J Find the work done if a 50 N force moves an object 3 m at an angle of 60°. Work = Force \* Distance \* cos(θ) = 50 N \* 3 m \* cos(60°) = 75 J What is the power output of an escalator lifting a 75 kg person 10 m in 15 seconds? Power = (m \* g \* h) / Time = (75 kg \* 9.8 m/s² \* 10 m) / 15 s = 490 W What is the efficiency of a machine that inputs 1000 J and outputs 800 J? Efficiency = (Output Energy / Input Energy) \* 100 = (800 J / 1000 J) \* 100 = 80% A wave has a frequency of 250 Hz and a wavelength of 1.2 m. What is its speed? Speed = Frequency \* Wavelength = 250 Hz \* 1.2 m = 300 m/s A sound wave has a speed of 340 m/s and a wavelength of 0.85 m. What is its frequency? Frequency = Speed / Wavelength = 340 m/s / 0.85 m = 400 Hz A transformer increases voltage from 120 V to 240 V. If the primary coil has 100 turns, how many turns does the secondary coil have? Turns in secondary = (Secondary Voltage / Primary Voltage) \* Turns in primary = (240 V / 120 V) \* 100 = 200 A circuit has a voltage of 24 V and a resistance of 8 Ω. What is the current? Current = Voltage / Resistance = 24 V / 8 Ω = 3 A A motor uses 500 W of power and operates at 250 V. What is the current? Current = Power / Voltage = 500 W / 250 V = 2 A A force of 15 N is applied to an object over a distance of 5 m. How much work is done? Work = Force \* Distance = 15 N \* 5 m = 75 J A 100 W lightbulb operates for 5 hours. How much energy does it use? Energy = Power \* Time = 100 W \* 5 h \* 3600 s/h = 1.8 MJ A car is moving at 72 km/h. Convert this speed to m/s. Speed = (72 km/h \* 1000 m/km) / (3600 s/h) = 20 m/s A light wave takes 8 minutes to travel from the Sun to Earth. How far is Earth from the Sun? Distance = Speed \* Time = (3.0 x 10⁸ m/s) \* (8 \* 60 s) = 1.44 x 10⁸ km A wave has a speed of 1500 m/s and a frequency of 500 Hz. What is its wavelength? Wavelength = Speed / Frequency = 1500 m/s / 500 Hz = 3 m