QUESTION FOR SHORT ANSWER
Q.1 In a tug of war, three men pull on a rope to the left at A and three men pull to the right at B with forces of
equal magnitude. Now a weight of 5.0 lb is hung vertically from the center of the rope.
(a) Can the men get the rope AB to be horizontal?
(b) If not, explain. If so, determine the magnitude of the forces required at A and B to do this.
Q.2 A massless rope is strung over africtionless pulley. A monkey holds onto one end of the rope and a
mirror, having the same weight as the monkey, is attached to the other end of the rope at the mankey's
level. Can the monkey get away from his image seen in the mirror.
(a) by climbing up the rope
(b) by climbing down the rope
(c) by releasing the rope?
Q.3 A student standing on the large platform of a spring scale notes his weight. He then takes a step on this
platform and noticed that the scale reads less than his weight at the beginning of the step and more than
his weight at the end of the step. Explain.
Q.4 An object is placed far away from all the objects that can exert force on it. A frame of reference is
constructed by taking the origin and axes fixed in this object. Will the frame be necessarily inertial?
Q.5 The acceleration of a particle is zero as measured from an inertial frame of refrence. Can we conclude
that no forces acts on the particle?
Q.6 Two blocks of unequal masses are tied by a spring. The blocks are pulled stretching the spring slightly
and the system is released on a frictionless horizontal platform. Are the forces due to the spring on the
two blocks equal and opposite? If yes, is it an example of Newton's third law?
Q.7 How could a person who is at rest on completely frictionless ice covering a pond reach shore? Could he
do this by walking, rolling, swinging his arms, or kicking his feet? How could a person be placed in such
a position in the first place?
Q.8 If you want to stop the car in the shortest distance on an ice road, should you
(a) push hard on the brakes to lock the wheels, (b) push just hard enough to prevent slipping, or (c)
"pump" the breakes?
Q.9 How does the earth's rotation affect the apparent weight of a body at the equator?
Q.10 Suppose you need to measure whether a table top in a train is truly horizontal. If you use a spirit level can
you determine this when the train is moving down or up a grade? When the train is moving along a curve?
Q.11 A classroom demonstration of Newton's first law is as follows: A glass is covered with a plastic card and
a coin is placed on the card. The card is given a quick strike and the coin falls in the glass.
(a) Should the friction coefficient between the card and the coin be small or large?
(b) Should the coin be light or heavy?
(c) Why does the experiment fail if the card is gently pushed?
Q.12 Can a sailing boat be propelled by air blown at the sails from a fan attached to the boat?
Q.13 Why is it difficult to walk on sand?
Q.14 Explain why a man getting out of a moving train must run in the same direction for a cerain distance.
Q.15 During a high jump event, it hurts less when an athlete lands on a heap of sand. Explain.
Q.16 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?
Q.17 A woman in an elevator lets go of her briefcase but it does not fall to the floor. How is the elevator
moving?
Q.18 You take two identical tennis balls and fill one with water. You release both balls simultaneously from the
top of a tall building. If air resistance is negligible, which ball strikes the ground first? Explain. What is the
answer if air resistance is not negligible?
Q.19 "A ball is thrown from the edge of a high cliff. No matter what the angle at which it is thrown, due to air
resistance, the ball will eventually end up moving vertically downward." Justify this statement.
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