Advertisements
Advertisements
Question
The speed of sound in air is about 330 ms-1. Express this speed in kmh-1. How long will the sound take to travel 99 km?
Solution
Speed of sound in air = 330 m/sec
∴ Speed in km/h = `(330xx60xx60)/1000`
= 1118 km/h
Time taken by sound to cover 99 km
= `99/1188=1/12` hours
= `1/12xx60` = 5 minutes
or 5 × 60 = 300 seconds
APPEARS IN
RELATED QUESTIONS
A and B take 6 hours and 9 hours respectively to complete a work. A works for 1 hour and then B works for two hours.
(i) How much work is done in these 3 hours?
(ii) How much work is still left?
Mohit can complete a work in 50 days, whereas Anuj can complete the same work in 40 days. Find:
(i) work done by Mohit in 20 days.
(ii) work left after Mohit has worked on it for 20 days.
(iii) time taken by Anuj to complete the remaining work.
Shaheed can prepare one wooden chair in 3 days and Shaif can prepare the same chair in 4 days. If they work together, in how many days will they prepare:
(i) one chair?
(ii)14 chairs of the same kind?
Jagan went to another town such that he covered 240 km by a car going at 60 kmh-1. Then he covered 80 km by a train, going at 100 kmh-1 and the rest 200 km, he covered by a bus, going at 50 kmh-1. What was his average speed during the whole journey?
| S.No | Speed | Distance | Time (Hours) |
| i | 35 Km/hour | 280 Km | |
| ii | 40 Km/hour | 360 Km | |
| iii | 45 Km/hour | 315 Km | |
| iv | 50 Km/hour | 300 Km | |
| v | 55 Km/hour | 275 Km |
Wilson reached 240 Km at the speed of 60 Km/hour. How much time did he travelled?
Nazar travelled 360 Km at the speed of 90 Km/hour. Find the time taken for his travel
These log boats do not go very far. If the wind is helpful, then travel about 4 km in one hour.
Guess how far you can go in one hour if you walk fast.
Name two things that are lying to your west.
Look at the different types of boats.
Some boats have motors and go further into the sea. since they go far out they can catch more fish. These boats travel faster, at a speed of about 20 km in one hour.
How much time will they take to go 85 km?
