Hi A car travels 43 km in 56 minutes.

What is its average speed in km/h?

Give your answer rounded to 1 decimal place.

Step-by-step explanation:

Use the average speed formula.

56 minutes = 0.933333 hours

54.88 mph

Step-by-step explanation: the Doppler effect formulae is given below as

f' = (v + vo) /(v - vs) × f

Where f' = observed frequency = 236 Hz,

f = frequency of sound source (stationary frequency) = 253 Hz.

v = speed of sound in air = 761 mph

Since the car (source) is moving away relative to the observer, vs will have a negative value (-vs)

vo = 0 mph ( since the observer is not moving)

By substituting the parameters, we have that

236 = (761+0)/(761 - (-vs)) × 253

236 = (761/ 761 +vs) × 253

By cross multiplication, we have that

236 × (761 +vs) = 761 ×253

761 + vs = 761 ×253/ 236

761 + vs = 192533/ 236

761 + vs = 815.88

vs = 815.88 - 761

vs = 54.88 mph