10-26-2010, 07:39 PM
[FONT="][FONT="]Q # 1:Consider a box that is placed on different surfaces. Marks = 10[/FONT]
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a) In which situation (s) is there no force acting on the box?
b) In which situation (s) is there a static friction force acting on the box?
c) In which situation (s) is there a kinetic friction force acting on the box?
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[FONT="]Various possible situations are as under:
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[FONT="]I. The box is at rest on a rough horizontal surface.
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[FONT="]II. The box is at rest on a rough tilted surface.[/FONT]
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III. The box is on the rough-surfaced flat bed of a truck- the truck is moving at a constant velocity on a straight, level road and the box remains in the same place in the middle of the truck bed.[/FONT]
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IV. The box is on the rough-surfaced flat bed of a truck- the truck is speeding up on a straight, level road, and box remains in the same place in the middle of the truck bed.[/FONT]
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V. The box is on the rough-surfaced flat bed of a truck- the truck is climbing a hill, and the box is sliding towards the back of the truck.[/FONT]
Q # 2 A spaceship is moving in the vacuum of outer space, far from any planet, when its engine dies. As a result, the spaceship slows down and stops. What does Newton‘s first law say about this event? Marks = 5
Solution:-
In this situation there are no forces acting on the spaceship, so according to Newton’s first law, it will not stop. It continues to move in a straight line with constant speed, some science fiction movies have made use of very accurate science; this was not one of them. [/FONT]
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[FONT="]Q # 3: A traffic light of weight W hangs from two light cables; one on each side of the light. Each cable hangs at a 450 angle from the horizontal. What I the tension in each cable? Marks = 5[/FONT]
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a) In which situation (s) is there no force acting on the box?
b) In which situation (s) is there a static friction force acting on the box?
c) In which situation (s) is there a kinetic friction force acting on the box?
[/FONT]
[FONT="]Various possible situations are as under:
[/FONT]
[FONT="]I. The box is at rest on a rough horizontal surface.
[/FONT]
[FONT="]II. The box is at rest on a rough tilted surface.[/FONT]
[FONT="]
III. The box is on the rough-surfaced flat bed of a truck- the truck is moving at a constant velocity on a straight, level road and the box remains in the same place in the middle of the truck bed.[/FONT]
[FONT="]
IV. The box is on the rough-surfaced flat bed of a truck- the truck is speeding up on a straight, level road, and box remains in the same place in the middle of the truck bed.[/FONT]
[FONT="]
V. The box is on the rough-surfaced flat bed of a truck- the truck is climbing a hill, and the box is sliding towards the back of the truck.[/FONT]
Q # 2 A spaceship is moving in the vacuum of outer space, far from any planet, when its engine dies. As a result, the spaceship slows down and stops. What does Newton‘s first law say about this event? Marks = 5
Solution:-
In this situation there are no forces acting on the spaceship, so according to Newton’s first law, it will not stop. It continues to move in a straight line with constant speed, some science fiction movies have made use of very accurate science; this was not one of them. [/FONT]
[FONT="]
[/FONT]
[FONT="]Q # 3: A traffic light of weight W hangs from two light cables; one on each side of the light. Each cable hangs at a 450 angle from the horizontal. What I the tension in each cable? Marks = 5[/FONT]