22 APPLIED MECHANICS 
diameter, andL.su Gtiege tigenghc © 6s: aearipe:. ied tae aeaien ae 
in eter, and are driven h5tol the 
So cadlinnne ne osopul OF fies Recoieedloh tie manta poare "ary 
$. The opsed of a tain Tecreaben ot a. tallecan aee Soom 0 SS G0 mieten 
hour in 1 minute 20 seconds. What is the acceleration in feet per second per 
second ? 
9. A rotating wheel increases its speed from 100 to 250 revolutions per 
minute in 35 seconds. What is the mean angular acceleration in radians per 
second per second ? 
10. A body starts from rest and its velocity increases at the uniform rate of 
Sit pee econ ee How long will it take to travel 144 feet? 
11. A moving body has its velocity reduced 2 feet per second in each second 
while it moves a distance of 45 feet, and its velocity is then 4 feet per second. 
What was the initial velocity of the body? 
12. A stone is dropped into a well, and after the lapse of 2-5 seconds the sound 
of the splash is heard. Taking the velocity of sound as 1100 feet per second, 
calculate the depth to the water in the weil. 
appear i araer atime Pigmre c tot eet ot phe pedo he 
an hour and it is brought to rest, covering a distance of 220 yards during the 
time of application of the brakes. Assuming the retardation to be uniform, find 
the time of action of the brakes. 
14. The speed of a motor car is determined by observing the times of passing 
a number of posts placed 500 feet apart. whe’ kisan et ‘eovectboge tins iolanaot 
between the first and second posts was 20 seconds, and between the second and 
third 19 seconds. If the acceleration of the car is constant, find its 
in feet per second per second, and also the velocity in miles per hour at the 
instant it passes the first post. [Inst.C.E_] 
15. A rotating wed ee eee 
second while it makes 300 revoluti yb pr eateiey spp hoer Bed aguas oe 76 
minute. What was the initial f the wheel in revolutions per minute? 
Also, what was the time occupied in the above reduction in speed ? 
16. The wheels of a motor car are 30 inches in diameter, what is their 
angular velocity in revolutions per minute and in radians per second when the 
speed of the car is 20 miles per hour? If the car is brought to rest in a distance 
of 60 yards under a uniform xehensiatdans whan te Sie AaGar Tpit SP 
wheels in radians per second per second ? 
17. Determine the apparent velocity and direction of rain-drops falling 
vertically with a velocity of 20 feet per second with reference to a bicyclist 
moving at the rate of 12 miles an hour. [inst.C.E.] 
18. A cyclist is riding due west at a speed of 12 miles per hour, and the 
wind is at the time blowing from the south-east with a speed of 5} miles per 
hour. If the cyclist Car ee eee ee 
At what speed would the cyclist require to ride if the flag is to fly due north? 
19. A man standing on a train which is moving with a ett ats 
hour shoots at an object running away from the railway at right angles at 
speed of 12 miles per hour. Tf the bullet’ Whick ts eappoued i 
horizontal straight line, has a velocity of 880 feet per second, and if the line 
connecting man and object makes an angle of 45° with the train when he fires, 
E.] 
ina 
Raat e 
find at what angle to the train he must aim in order to hit the object. 
20. A and B-are two points in a rigid body. A and B are moving in 
vertical plane, and when AB is inclined at 30° to the 
horizontal A is moving in a horizontal direction with 
a velocity of 10 feet per second. At the same instant 
the point B is moving in a vertical direction. Find 
the velocity of the point B. 
21. AC and BD (Fig. 19) are.two cranks which 
