Answer:
a) The average speed of the record race is 35.2 km/h
b) The time it will take to cover the first half is 2h 42 min
Explanation:
a) The average speed of the record race is calculated dividing the total distance over time:
v = distance/ time
So let´s write the time in hours:
if 60 s is 1 min, then 37 s will be (37 s · 1 min/60 s) 0.62 min.
If 60 min is 1 h, then 40.62 min will be (40.62 min · 1 h/60 min) 0.68 h
Then, the record time is 5.68 h
The average speed will be:
v = 2.00 × 10² km / 5.68 h = 35.2 km/h
b) Now we have the speed and the distance and have to find the time it will take the skater to cover that distance:
The speed will be:
v = 1.05v = 1.05 · 35.2 km/h = 37.0 km/h
The distance will be:
2.00 × 10² km /2 = 1.00 × 10² km
Then:
v = distance/ time
time = distance /v = 1.00 × 10² km / 37.0 km/h = 2.70 h
If 1 h is 60 min, 0.70 h will be (0.70 h · 60 min/h) 42 min.
The time it will take to cover the first half is 2h 42 min
