a racer completes a 500km in exactly 2hr and 15 min. what is the average speed of the car in kilometers per hour and meters per second?
回答 (2)
2018-01-12 6:01 pm
Average speed
= Distance / Time
= (500 km) / (2 hr 15 min)
= (500 km) / [2 hr + (15/60) hr]
= (500 km) / (2.25 hr)
= (222 and 2/9) km/hr
≈ 222 km/hr (to 3 sig. fig.)
Also, average speed
= (500 km) / (2.25 hr)
= (500 × 1000 m) / (2.25 × 3600 s)
= (61 and 59/81) m/s
≈ 61.7 m/s (to 3 sig. fig.)
= Distance / Time
= (500 km) / (2 hr 15 min)
= (500 km) / [2 hr + (15/60) hr]
= (500 km) / (2.25 hr)
= (222 and 2/9) km/hr
≈ 222 km/hr (to 3 sig. fig.)
Also, average speed
= (500 km) / (2.25 hr)
= (500 × 1000 m) / (2.25 × 3600 s)
= (61 and 59/81) m/s
≈ 61.7 m/s (to 3 sig. fig.)
2018-01-13 2:17 pm
Speed = Distance/Time
15min (1hr/60min) = 0.25hr
Speed = 500km/(2.25hr) = 222.222222222222222 km/hr
So either 222 km/hr or 222.2 km/hr would be good answers
222.2222222k/hr (1000m/1km)(1hr/60min)(1min/60sec)
= 61.728395061728395 m/s
So either 61.7 m/s or 61.73 m/s would be good answers
15min (1hr/60min) = 0.25hr
Speed = 500km/(2.25hr) = 222.222222222222222 km/hr
So either 222 km/hr or 222.2 km/hr would be good answers
222.2222222k/hr (1000m/1km)(1hr/60min)(1min/60sec)
= 61.728395061728395 m/s
So either 61.7 m/s or 61.73 m/s would be good answers
參考: Here's a very short 2 minute video on how to work 'unit cancellation' and conversion problems.
https://www.youtube.com/watch?v=8jB-LaTGgq8
Note: In the problem above, I'll typically have the converter in (parens). Converters = (1)
收錄日期: 2021-04-18 18:02:40
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