Answer
a) It would take 10 s to run 100.0 m.
b) The speed is 9.8 meters per second.
c) It would take 1.5 * $10^{2}$ s to run 1.45 km
Work Step by Step
a) 100 yd in 9.3 s
1 m = 1.094 yd
1.094 yd = 1 m
1 yd = 1 / 1.094 m = 0.9140767824 m
100 yd = 91.40767824 m
.
So the sprinter runs 91.40767824 m in 9.3 s.
This is 1 m in 9.3/91.40767824 s = 0.101742 s
So 100.0 m in 10.1742 s.
Rounding to 2 significant figures gives 10 s.
b) Speed is 100 yd per 9.3 s
100 yd = 91.40767824 m (see a),
so speed is 91.40767824 m per 9.3 s.
This is the same as 91.40767824 / 9.3 per second, which is 9.828782606 meters per second.
Rounding to 2 significant figures gives 9.8 meters per second.
c) velocity = distance / time
so time = distance / velocity
distance = 1.45 km = 1450 m
velocity = 9.828782606 meters per second
So time = 1450 / 9.828782606 = 147.5259s
Rounding to 2 significant figures gives 1.5 * $10^{2}$ s
