Question

In the hare-tortoise race,the hare ran for 2 min. at a speed of 7.5km/h,slept for 56 min. and again ran for 2 min. at a speed of 7.5km/h. Find the average speed of the hare in race

Answer 1

D1 = 7.5×2/60= 0.25km

D2= 7.5×2/60= 0.25km

Total Distance= 0.25+0.25=0.50km

Total time taken = 2+2+56=60min= 1 HR

Average speed =total distance/ total time
Average speed= 0.50/1= 0.50 km/hr

Answer 2

Answer:

The average speed of hare in race is 0.138 m/s or 0.4968 km/hr.

Explanation:

$\mathrm{V}_{1}$ = 7.5 Km/hour = 7.5 x 1000/3600 = 2.08 m/s

$D_{1}$ = distance = $\mathrm{V}_{1}$ x t = 2.08 x 120 = 249.6 meter

Duration of sleep = $\mathrm{t}_{2}$ = 56 min

Velocity during sleeping period = $\mathrm{V}_{2}$ = 0 m/s

Hence $\mathrm{D}_{2}=\mathrm{V}_{2} \mathrm{x} \mathrm{t}_{2}$ = 0 meter

Now $\mathrm{t}_{3}$ = 2 min,

$\mathrm{V}_{3}$ = 7.5 Km/h = 2.08 m/s

$D_{3}$ = 2.08 x 120 = 249.6 meter

Total duration = $\bold{\mathrm{T}=\mathrm{t}_{1}+\mathrm{t}_{2}+\mathrm{t}_{3}}$ = 60 min = 3600 seconds

Total distance travelled = $\bold{\mathrm{D}=\mathrm{D}_{1}+\mathrm{D}_{2}+\mathrm{D}_{3}}$ = 499.2 meter

Hence Average speed of hare = Total distance / total duration = 499.2 / 3600 = 0.138 m/s