7/29/2019 Test Mechanics

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1. A ball is released from the top of a tower of height h metres. It takes Tseconds to reach the ground. What is the position of the ball in T/3

seconds?

2. A bomb of mass 16 kg at rest explodes into two pieces of masses of 4 kg and12 kg. The velocity of the 12 kg mass is 4 m/s. What is thekinetic energyof

the other mass ?

3. A car is travelling at 20 m s-1. A compass on the dashboard tells the drivershe is

travelling in a direction 25 east of magnetic north. Find the component of

the cars

velocity in a northerly direction? (Ans: 18m/s)

4. Why are liquid drops spherical in shape?5. What is the dimensional formula of the quantity Q= force X velocity X time?6. Give the significance of the stress- strain graph.7. A toy rocket is projected vertically upwards from the ground, with an initial

velocity of

30 m s-1. Calculate the maximum height reached. (Ans: 46m)

8. Draw the graph showing the variation of the force of friction with appliedforce.

9. What is the effect of height on the value of acceleration due to gravity? Proveby mathematical calculations.

OR

What is the effect of depth on the value of acceleration due to gravity? Prove

by mathematical calculations.

10.Explain Parallax method to find the distance of the distant star from theearth.

11.Two vectors have equal magnitude, and their scalar product is one-third ofthe square of their magnitude. Find the angle between them. (Ans: 70)

12.A body is moved from the surface of the earth to a point R equal to itsradius above the earth. Calculate the work done during process.

13.A firefighter 50m away from a burning building directs a stream of waterfrom a fire hose at an angle of 30 above the horizontal as shown below. If the

speed of the stream is 40m/s, at what height will the water strike the

building?

Ans. h = 18.7m.

14.State the parallelogram law of vector addition. Derive the expression for themagnitude of the resultant of the two vectors.

15.16.Human blood has a density of approximately 1.05 x 103 kg/m3. Use this

information to estimate the difference in blood pressure between the brain

and the feet in a person who is approximately six feet tall. (Ans: 19kPa)

17.Define terminal velocity and derive the expression for the same in terms ofthe coefficient of viscosity of the liquid. Compare the value of the terminal

velocity for the two balls one of radius 1cm and the other which is formed by

combination of 27 such drops.

Or

State and prove Bernoullis theorem.

Assuming that the blood flow rate depends only on the pressure gradient,the viscosity and the radius R of the artery, give a proof using dimensions,and showing all your steps, that the flow rate is proportional to R4. If plaquebuild up in an artery reduces its radius by 10%, estimate how much theblood flow is reduced if the blood pressure stays the same.