Question

Solve these word problems:-
1) A car covers a distance of 22 km/h in 20 minutes. What is its speed in km/h ?

2) An athlete covers 400m in 40 seconds. Find:-

a) his speed
b) distance covered by him in 20 minutes
c) time taken by him to cover 875 m.

3) Convert the following speeds:-
a) 450 km/h into m/a
b) 35 m/s into km/h
c) 1224 km/h into km/min

4) Which is greater:-
a) a speed of 130 km/ h or
b) a speed of 38 m/s ?

5) A 80 m long train crosses a 60 m platform in 9 seconds. Find the speed of the train in km/h.​

Answer 1

Answer:

1) Given: Distance= 22km/h

Time= 20 min. = 20/60 = 1/3 h.

So applying formula

Speed= Distance/Time

hence

= 22km/h / 1/3 h

= 22*3 km/h

= 66 km/h

2) Given: Distance = 400 m

Time = 40 sec.

a) Speed= Distance/time

= 400/ 40

= 10m/s

b) Given: Time= 20 min.= 20*60= 1200 sec

Speed= 10m/s

Distance= Speed*Time

= 10* 1200

= 12000 m/s

= 12 km/ h

c) Given: Distance= 875 m ; Speed= 10m/s

Time=?

Speed= Distance/time

so time= distance/speed

= 875/10

= 87.5 sec

3) b) 35m/s into km/h

= 35*18/5

= 126 km/h

c) 1224km/h into 1224km/min.

= 1224km*60min

= 73440km/min.

4) a) Speed= 130km/h

= 130*5/18

= 361 m/s

b) Speed= 38m/s

So option(a) speed is greater.

5) Total length or distance = 80+60 = 140m

Time = 9sec

Speed = Distance/ Time

= 140/ 9

= 15.5 m/s

= 15.5 * 5/18

= 4.30 km/h