Berikut ini adalah pertanyaan dari moonshingun pada mata pelajaran Matematika untuk jenjang Sekolah Menengah Atas
3. In an athletic competition, a javelin thrower threw a javelin over a distance of 76.5 m. While in flight, the javelin travelled at an average speed of 15.0 m/s. How long did the javelin remain in the air?
4. Cyclists A and B cycled at an average speed of 15 km/h and 20 km/h respectively from the same starting point X on the same route. Cyclist B started his journey 6 min after cyclist A started.
a. What were the distances travelled by cyclists A and B 1 h after cyclist A started his journey from point X?
b. Did cyclist B overtake cyclist A within the first hour of cyclist A's journey?
Jawaban dan Penjelasan
Berikut ini adalah pilihan jawaban terbaik dari pertanyaan diatas.
Jawab:
a. Car B travelled at a higher average speed because it took less time to cover the distance between towns X and Y than Car A. b. To calculate the average speeds of cars A and B, we can use the formula:
average speed = total distance / total time
For Car A, the total distance is 62,500 m and the total time is 50 minutes (8:50 am - 8:00 am). Converting 50 minutes to hours, we get:
total time = 50 minutes / 60 minutes/hour = 0.83 hours
Therefore, the average speed of Car A is:
average speed = 62,500 m / 0.83 hours = 75,301 m/h
For Car B, the total distance is the same (62,500 m), but the total time is 40 minutes (8:55 am - 8:15 am) or 0.67 hours. Therefore, the average speed of Car B is:
average speed = 62,500 m / 0.67 hours = 93,284 m/h
So, Car B travelled at a higher average speed than Car A.
We can use the formula:
distance = speed x time
to find the time the javelin remained in the air. Rearranging the formula, we get:
time = distance / speed
Substituting the given values, we get:
time = 76.5 m / 15.0 m/s = 5.1 s
Therefore, the javelin remained in the air for 5.1 seconds.
a. To find the distances travelled by cyclists A and B 1 hour after cyclist A started his journey from point X, we can use the formula:
distance = speed x time
For cyclist A, the speed is 15 km/h and the time is 1 hour. Therefore, the distance travelled by cyclist A is:
distance = 15 km/h x 1 hour = 15 km=
For cyclist B, the speed is 20 km/h and the time is 1 hour minus 6 minutes (or 0.1 hour) because cyclist B started 6 minutes later than cyclist A. Therefore, the distance travelled by cyclist B is:
distance = 20 km/h x (1 hour - 0.1 hour) = 18 km
b. To determine whether cyclist B overtook cyclist A within the first hour of cyclist A's journey, we can compare their distances travelled at the end of the first hour. After 1 hour, cyclist A has travelled 15 km, while cyclist B has travelled 18 km. Therefore, cyclist B has overtaken cyclist A within the first hour of cyclist A's journey.
Penjelasan dengan langkah-langkah:
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Last Update: Fri, 09 Jun 23