Speed Time And Distance - Study Mode

[#226] A car travels at a speed of 60 km/hr and covers a particular distance in one hour. How long will it take for another car to cover the same distance at 40 km/hr ?
Correct Answer

(C) $$frac{3}{2}$$ hours

Explanation

Solution: Total distance = 60 km/hr × 1 hour = 60 km Therefore, Time will be taken by another car to travel the same distance with 40 km/hr = $$frac{60}{40}$$ = $$frac{3}{2}$$ hours

[#227] A man walking at the rate of 5 km/hr crosses a bridge in 15 min. The length of the bridge (in metres) is :
Correct Answer

(D) 1250 metres

Explanation

Solution: $$eqalign{
& 15min = frac{1}{4}{ ext{hrs}} cr
& { ext{1 hr }} o { ext{5 kms}} cr
& frac{1}{4}{ ext{hr}} o frac{5}{4}{ ext{ kms}} cr
& { ext{So, length of the bridge}} cr
& = frac{5}{4}{ ext{ km}} cr
& { ext{ = 1250 metres}} cr} $$

[#228] A gun is fired at a distance of 1.7 km from Ram and he hears the sound after 25 seconds. The speed of sound in meter per second is
Correct Answer

(D) 68 m/s

Explanation

Solution: $$eqalign{
& { ext{Distance = 1}}{ ext{.7 km}} cr
& { ext{Time = 25 sec}} cr
& herefore { ext{Speed = }}frac{{{ ext{Distance}}}}{{{ ext{Time }}}} cr
& ,,,,,,,,,,,,,,,,,,,,, = frac{{1.7 imes 1000}}{{25}} cr
& ,,,,,,,,,,,,,,,,,,,,, = 68{ ext{ m/s}} cr} $$

[#229] A man crosses a road 250 metres wide in 75 seconds. His speed in km/hr is :
Correct Answer

(B) 12 km/hr

Explanation

Solution: $$eqalign{
& S = frac{D}{T} = frac{{250}}{{75}}{ ext{ m/sec}} cr
& ,,,,,,,,,,,,,,,,,,{ ext{ = }}frac{{250}}{{75}} imes frac{{18}}{5} cr
& ,,,,,,,,,,,,,,,,,,, = 12{ ext{ km/hr}} cr} $$

[#230] The speed of 90 km per hour is same as :
Correct Answer

(C) 25 m/s

Explanation

Solution: 1 km/hr = $$frac{5}{18}$$ ∴ 90 km/hr = 90 × $$frac{5}{18}$$
= 25 m/s