Doppler Effect — Grade 12 Past Paper Questions

A bat flying toward a cliff at constant speed emits sound waves that reflect back. Name and state the Doppler effect, show the emitted frequency follows a specific form, and calculate the bat's speed when reflected frequency exceeds emitted frequency by 850 Hz.

A stationary listener records sound wavelength from a moving police siren using a wavelength-time graph. Name the Doppler phenomenon causing wavelength changes, determine whether the car travels toward or away from the listener, and calculate the siren's frequency and the car's velocity magnitude.

A stationary listener records frequency from a police siren as the car approaches at 26 m·s⁻¹, passes, then recedes. State the Doppler effect, calculate sound speed using two recorded frequencies, determine the siren's wavelength, and sketch frequency versus time with passing moment marked.

A car approaching a stationary sound device that emits 24,000 Hz waves and detects reflected waves. State the Doppler effect, calculate the reflected frequency from the moving car, and explain how spectral line shifts from a distant star indicate its motion away from Earth.

A learner moves toward a stationary sound source observing frequency changes. Name the phenomenon, identify a medical application, determine proportionality type, calculate velocity from gradient 1.06, and sketch how higher velocity affects the frequency-relationship graph.

An ambulance siren first stationary, then moving toward a man with a detector. Calculate the stationary-source wavelength, state the Doppler effect, explain how wave spacing and frequency change as the ambulance approaches, and calculate the ambulance's speed from the wavelength change of 0.05 m.

Learners graph frequency ratio versus listener velocity toward a stationary sound source. State the Doppler effect, determine listener motion direction, identify the physical quantity the gradient represents, and calculate the speed of sound in air.

Listener traveling toward a sound source at different speeds. State Doppler effect, analyze how speed and intensity affect observed frequency, calculate new source frequency when observed frequency stays constant despite speed increases, and identify a receding star's absorption spectrum.

Multiple-choice page covering Doppler shift of spectral lines from a moving star and the relationship between electric field magnitude and point charge at a fixed distance.

Multiple-choice questions covering impulse direction and velocity changes in bouncing objects, and the Doppler effect for light from distant stars.

Multiple-choice questions covering which physical quantity changes as a hot-air balloon descends at constant speed, and Doppler shift interpretation for an ambulance siren.

Multiple-choice page covering Doppler shift from a moving police siren and electrostatic forces and charge redistribution between three point charges when identical spheres touch and separate.

Multiple-choice page covering net forces in projectile motion, conservation laws in inelastic collisions, work-energy relationships, Doppler effect, and electrostatic forces.

Multiple-choice page covering red-shift observation of star spectra to determine recession, and the electric field pattern from two charged spheres to identify their polarities.

Multiple-choice page covering the Doppler effect with a moving listener and the electric field vector addition from two equal negative point charges at a common distance.

Multiple-choice questions on momentum conservation when a person jumps from a skateboard, total mechanical energy of falling objects, and wavelength changes in the Doppler effect.