Question

100 баллов 1. За 10 с велосипедист проїхав 200 м, за наступні 20 с — ще 700 м. Знайдіть середню швидкість руху велосипедиста на всьому шляху. 2.Мотоцикліст проїхав 20 км за 45 хв, а потім їхав зі швидкістю 60 км/год протягом 1,5 год. Яка була його середня швидкість на всьому шляху? 3.Автомобіль перші 30 хв свого шляху рухався зі швидкістю 40 км/год, а наступні 2 год зі швидкістю 50 км/год. Визначте середню швидкість руху автомобіля на всьому шляху.

Answer 1

Ответ: 30м/с; 48,89км/ч; 48км/ч

Объяснение:

Дано:

t1=10c

S1=200м

t2=20c

S2=700м

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Vср-?

Vср=S/t=(S1+S2)/(t1+t2)=(200+700)/(10+20)=30м/с

Дано:

S1=20км

t1=45мин=0,75ч

V2=60км/ч

t2=1,5ч

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Vср-?

Vср=S/t=(S1+V2t2)/(t1+t2)=(20+60*1,5)/(0,75+1,5)=48,89км/ч

Дано:

t1=30мин=0,5ч

V1=40км/ч

t2=2ч

V2=50км/ч

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Vср-?

Vср=S/t=(V1t1+V2t2)/(t1+t2)=(40*0,5+50*2)/(0,5+2)=48км/ч

Answer 2

Calculating Average Speed for Different Time Intervals

1. The average speed of a cyclist for the entire journey can be calculated by dividing the total distance traveled by the total time taken.

- For the first 10 seconds, the cyclist traveled 200 meters. - For the next 20 seconds, the cyclist traveled an additional 700 meters.

The total distance traveled is 200m + 700m = 900m, and the total time taken is 10s + 20s = 30s.

Therefore, the average speed of the cyclist for the entire journey is: \[ \text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{900m}{30s} = 30 \, \text{m/s} \]

2. For the motorcyclist: - The first leg of the journey covered 20 km in 45 minutes. - The second leg of the journey covered 60 km/h for 1.5 hours.

The total distance traveled is 20km + 60km = 80km, and the total time taken is 45 minutes + 1.5 hours = 2.25 hours.

Therefore, the average speed of the motorcyclist for the entire journey is: \[ \text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{80km}{2.25h} = 35.56 \, \text{km/h} \]

3. For the car: - The first 30 minutes were covered at 40 km/h. - The next 2 hours were covered at 50 km/h.

The total distance traveled is 40km + 100km = 140km, and the total time taken is 0.5 hours + 2 hours = 2.5 hours.

Therefore, the average speed of the car for the entire journey is: \[ \text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{140km}{2.5h} = 56 \, \text{km/h} \]