Speed, Time and Distance
- A man is walking at a speed of 10 kmph. After every km, he takes a rest for 5 minutes. How much time will he take to cover a distance of 5 km?
-
View Hint View Answer Discuss in Forum
Time taken in covering 5 Km = 5 = 1 hour 10 2
= 30 minutes
That person will take rest for four times.
∴ Required time
= (30 + 4 × 5) minutes
= 50 minutesCorrect Option: B
Time taken in covering 5 Km = 5 = 1 hour 10 2
= 30 minutes
That person will take rest for four times.
∴ Required time
= (30 + 4 × 5) minutes
= 50 minutes
- A car driver leaves Bangalore at 8.30 A.M. and expects to reach a place 300 km from Bangalore at 12.30 P.M. At 10.30 he finds that he has covered only 40% of the distance. By how much he has to increase the speed of the car in order to keep up his schedule?
-
View Hint View Answer Discuss in Forum
Distance covered by car in 2 hours
= 300 × 40 = 120 km 100
Remaining distance = 300 – 120 = 180 km
Remaining time = 4 – 2 = 2 hours∴ Required speed = 180 = 90 kmph 2 Original speed of car = 120 = 60 kmph 2
∴ Required increase in speed
= 90 – 60 = 30 kmphCorrect Option: D
Distance covered by car in 2 hours
= 300 × 40 = 120 km 100
Remaining distance = 300 – 120 = 180 km
Remaining time = 4 – 2 = 2 hours∴ Required speed = 180 = 90 kmph 2 Original speed of car = 120 = 60 kmph 2
∴ Required increase in speed
= 90 – 60 = 30 kmph
- A man travelled a distance of 80 km in 7 hrs partly on foot at the rate of 8 km per hour and partly on bicycle at 16km per hour. The distance travelled on the foot is
-
View Hint View Answer Discuss in Forum
Journey on foot = x km
Journey on cycle = (80 – x) km∴ x = 80 − x = 7 8 16 ⇒ 2x + 80 − x = 7 16
⇒ x + 80 = 16 × 7 = 112
⇒ x = 112 - 80 = 32 km.
Second Method :
Here, x = 80, t = 7
u = 8, v = 16Time = vt − x v − u = 16 × 7 − 80 16 − 8 = 112 − 80 8 = 32 = 4 hrs 8
Distance travelled
= 4 × 8 = 32 kmsCorrect Option: A
Journey on foot = x km
Journey on cycle = (80 – x) km∴ x = 80 − x = 7 8 16 ⇒ 2x + 80 − x = 7 16
⇒ x + 80 = 16 × 7 = 112
⇒ x = 112 - 80 = 32 km.
Second Method :
Here, x = 80, t = 7
u = 8, v = 16Time = vt − x v − u = 16 × 7 − 80 16 − 8 = 112 − 80 8 = 32 = 4 hrs 8
Distance travelled
= 4 × 8 = 32 kms
- Sarita and Julie start walking from the same place in the opposite directions. If Julie walks at a
of 2 km/hr, in how much time will they be 18 km apart ?speed of 2 1 km/hr and Sarita at a speed 2
-
View Hint View Answer Discuss in Forum
= 5 + 2 kmph = 9 kmph 2 2 Time = Distance = 18 Relative speed (9/2) = 18 × 2 = 4 hours 9 Correct Option: A
= 5 + 2 kmph = 9 kmph 2 2 Time = Distance = 18 Relative speed (9/2) = 18 × 2 = 4 hours 9
- You arrive at your school 5 minutes late if you walk with a speed of 4 km/h, but you arrive 10 minutes before the scheduled time if you walk with a speed of 5 km/h. The distance of your school from your house (in km) is
-
View Hint View Answer Discuss in Forum
If the required distance be = x km, then
x − x = 10 + 5 4 5 60 ⇒ 5x − 4x = 1 20 4 ⇒ x = 1 20 4 ⇒ x = 1 × 20 = 5 km. 4
Second Method :
Here, S1 = 4, t1 = 5
S2 = 5, t2 = 10Distance = (S1 × S2)(t1 + t2) S1 − S2 = (4 × 5)(5 + 10) 5 − 4 = 20 × 15 = 5 kms 60 Correct Option: B
If the required distance be = x km, then
x − x = 10 + 5 4 5 60 ⇒ 5x − 4x = 1 20 4 ⇒ x = 1 20 4 ⇒ x = 1 × 20 = 5 km. 4
Second Method :
Here, S1 = 4, t1 = 5
S2 = 5, t2 = 10Distance = (S1 × S2)(t1 + t2) S1 − S2 = (4 × 5)(5 + 10) 5 − 4 = 20 × 15 = 5 kms 60