PHYSICS : SHEET LAWS OF MOTION
LAWS OF MOTION THINKING PROBLEMS
1.
Explain why a man getting out of a moving train must run in the same direction for a certain distance.
2.
During a high jump event, it hurts less when an athlete lands on a heap of sand. Explain.
3.
An athlete runs over a certain distance before taking a long jump. Explain.
4.
Ripe mangoes fall down when the three is shaken. Why?
5.
A heavy picture frame is suspended by a string passing over a peg in the vertical wall and attached at its two ends to two points in the upper horizontal edge of the frame. Explain why the picture is likely to fall if the string is too short.
6.
Out of the coefficient of static friction, coefficient of kinetic friction and coefficient of rolling friction, the last is the least. True or false ?
7.
When we walk we rub our footwear opposite to the direction of motion. True or false ?
8.
Action and reaction are equal and opposite and so they balance each other. True or false ?
9.
The motion of the cm of a system is determined by external forces only and not the internal forces of the system. True or false ?
10. The momentum of a system of particles is always conserved. True or false? 11. What will be the trajectory of the bob of a pendulum if the string is cut when the bob is (a) at one of its extreme positions, (b) at its mean position. 12. Figure shows the position-time graph of a particle of mass m = 0.5 kg. Suggest a suitable example to fit the curve. What is the interval between ten consecutive impulses ? What is the magnitude of each impulse ? 13. A rod not reaching the rough floor is inserted between two identical blocks. A horizontal force F is applied to the upper end of the rod. Which of the blocks will move first ?
14. A massive homogeneous cylinder that can revolve without friction around a horizontal axis is secured on a flat car. A bullet flying horizontally with a velocity v strikes the cylinder and drops on to the car. Does the speed acquired by the car after the impact depend on the point where the bullet strikes the cylinder ? 15. The application of brakes on the driving wheels of a car means the reversal of the direction of the force of friction between the wheel and the ground. True or false ?
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