GS5. Which of the following is a greenhouse gas? University Of Sindh mcqs test

   

MOTION 

(PROBLEMS)

1. In an electron gun of a television set, an electron with an initial speed of 10^3m/s enters a region where it is electrically accelerated. It emerges out of the region after 1 micro second with speed of 4x10^5m/s. What is the maximum length of the electron gun? Calculate acceleration.

2. A car is waiting at a traffic signal and when it turns green, the car starts ahead with a constant acceleration of 2m/s^2. At the same time, a bus traveling with a constant speed of 10 m/s overtakes and passes the car. (a) How far beyond its starting point will the car overtake the bus? (b) How fast will the car be moving? 

3. A helicopter is ascending at a rate of 10m/s. At a height of 80m above the ground, a package is dropped. How long does the package take to reach the ground?

4. A boy throws a ball upward from the top of a cliff with a speed of 14.7m/s. On the way down it just misses the thrower and fall the ground 49 meters below. Find (i) How long the ball rises? (ii) How high it goes? (iii) How long it is in the air? (iv) with what velocity it strikes the ground.

5. A helicopter weighs 3920 newtons. Calculate the force on it if it is ascending at a rate of 2m/s^2. What will be force on helicopter if it is moving with the constant speed of 4m/s. 

6. A bullet having a mass of 0.005kg is moving with a speed of 100m/s. It penetrates into a bag of sand and is brought to rest after moving 25cm into the bag. find the decelerating force on the bullet. Also calculate the time in which it is brought to rest.

7. A car weighing 9800N is moving with a speed of 40km/h. On the application of the brakes, it comes to rest after travelling a distance of 50 meters. calculate the average retarding force.

8. An electron in a vacuum tube starting from rest is uniformly accelerated by an electric field so that it has a speed of 6 x 10^6m/s after covering is distance of 1.8cm. Find the force on the electron. Take the mass of electron as 9.1x10^31kg.

9. Two bodies A and B are attached to the ends of a string which passes over a pulley so that the two bodies hang vertically. If the mass of the body A is 4.8kg. Find the mass of body B which moves down with an acceleration of 0.2m/s^2. The value of g can be taken as 9.8m/s^2.

10. Two bodies of masses 10.2kg and 4.5kg are attached ot the two ends of a string which passes over a pulley in such a way that the body of mass 10.2kg lies on a smooth horizontal surface and the other ody hangs vertically. Find the acceleration of the bodies, the tension of the string and also the force which the surface exerts on the body of mass 10.2kg. 

11. A 100 grams bullet is fired from a 10kg gun with a speed of 1000m/2. What is the speed of recoil of the gun.

12. A 50 grams bullet is fired into a 10kg block that is suspended by a long cord so that it can swing as a pendulum. If the block is displaced so that its centre of gravity rises by 10cm, what was the speed of the bullet?

13. A machine gun fires 10 bullets per second into a target. Each bullet weights 20 gm and had a speed of 1500m/s. Find the force necessary to hold the gun in position 

14. A cyclist is going up a slope of 30° with a speed of 3.5m/s. If he stops pedaling, how much distance will he move before coming to rest? (Assume the friction to be negligible).

15. The engine of a motor car moving up 45° slope with a speed of 63km/h stops working suddenly. How far will the car move before coming to rest? (Assume the friction to be negligible).

16. In problem 15, find the distance that the car moves, if it weighs 19,600N and the frictional force is 2000N.

17. In the figure 3.22 find the acceleration of the masses and the tension in the string.

18. Two blocks are connected as shown in fig. 3.23. If the pulley and the planes on which the block are resting are frictionless, find the acceleration of the blocks and the tension in the string.

19. Two blocks each weighing 196N rest on planes as shown in fig. 3.24. If the planes and pulleys are frictionless, find the acceleration and tension in the cord.