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A brick is kept in three different ways on a table as shown in figure. The pressure exerted by the brick on the table will be (a) maximum in position A (b) maximum in position C (c) maximum in position B (d) equal in all cases

Answer: (a) maximum in position A Position A will have the highest pressure since the area of contact is the... View Article

A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in (i) polar regions (ii) deserts (iii) oceans (iv) tropical rainforests

Answer: (iv) tropical rainforests The animal described in the question, a carnivore with stripes on its body that moves very... View Article

A chapati maker is a machine which converts balls of dough into chapati. What effect of force comes into play in this process?

Answer: The force on the unit area is called pressure, which works on the chapati. This is the pressure that... View Article

A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?

Answer: The concentration of dissolved salts in seawater is higher than in drinking water. As a result, seawater will be... View Article

A father and son pushed their car to bring it to the side of the road as it had stalled in the middle of the road. They experienced that although they had to push with all their might initially to move the car, the push required to keep the car rolling was smaller, once the car started rolling. Explain.

Answer: Frictional force refers to the force generated by two surfaces that contact and slide against each other. Friction is... View Article

A forest is a purifier of __ and _

Answer: A forest is a purifier of air and water. By absorbing carbon dioxide and releasing oxygen, forests assist to... View Article

A gas-filled balloon moves up. Is the upward force acting on it larger or smaller than the force of gravity?

Answer: The upward force is larger than the force of gravity. Gravitational Force Each body in this universe attracts other... View Article

A girl is pushing a box towards the east direction. In which direction should her friend push the box so that it moves faster in the same direction?

Answer: Her friend should push the box in the direction of East, where it will begin to move faster as... View Article

A list of mediums is given below. (i) wood (ii) water (iii) air (iv) vacuum In which of these mediums can sound travel? (a) i & ii only (b) i, ii & iii only (c) iii & iv only (d) ii, iii & iv only

Answer: (b) i, ii & iii only To travel, sound required a medium. Sound cannot travel in a vacuum because... View Article

A man is pushing a cart down a slope. Suddenly the cart starts moving faster and he wants to slow it down. What should he do?

Answer: Man can accomplish the following He can start dragging the cart instead of pushing it to resist gravity’s downward... View Article

A marble is allowed to roll down an inclined plane from a fixed height. At the foot of the inclined plane, it moves on a horizontal surface (a) covered with silk cloth (b) covered with a layer of sand and (c) covered with a glass sheet. On which surface will the marble move the shortest distance. Give the reason for your answer.

Answer: Because it will exert a greater amount of friction on the marble, it will move the shortest distance on... View Article

A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be _ and _ .

Answer: A place receives very little rainfall, and the temperature is high throughout the year, the climate of that place... View Article

A simple pendulum makes 10 oscillations in 20 seconds. What is the time period and frequency of its oscillation?

Answer: Given parameters Time period (t) – 2s frequency (f) – 0.5 oscillations/sec A pendulum makes 10 oscillations in 20... View Article

A small hole P is made in a piece of cardboard. The hole is illuminated by a torch as shown in Fig. The pencil of light coming out of the hole falls on a mirror. At which point should the eye be placed so that the hole can be seen? (a) A (b) B (c) C (d) D

Answer: (a) A The eye should be placed at position A because the hole can be seen only when the... View Article

A star is ten light-years away from the earth. Suppose it brightens up suddenly today. After how much time shall we see this change?

Answer: 1 light-year= distance covered by light in one year. 10 light-years away from the earth glow today, then it... View Article

A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that (i) liquid A is a better conductor than liquid B. (ii) liquid B is a better conductor than liquid A. (iii) both liquids are equally conducting. (iv) conducting properties of liquid cannot be compared in this manner.

Answer: (i) liquid A is a better conductor than liquid B The amount of current flowing through a solution is... View Article

A tiny mirror M is fixed on a piece of cardboard placed on a table. The cardboard is illuminated by light from a bulb. The position of the eye with respect to the position of the bulb is shown in Fig. as A, B, C and D. In which position mirror will be visible? a. A b. B c. C d. D

Answer: (a) A When a ray of light from the bulb strikes the mirror M, according to the laws of... View Article

A toy car released with the same initial speed will travel farthest on (a) muddy surface (b) polished marble surface (c) cemented surface (d) brick surface

Answer: (b) polished marble surface Because a polished marble floor has the least frictional force and inertia, a car will... View Article

A water tank has four taps fixed at points A, B, C, D as shown in Fig. The water will flow out at the same pressure from taps at (a) B and C (b) A and B (c) C and D (d) A and C

Answer: (a) B and C B and C are at the same level, hence pressure will be the same at... View Article

Add the following: 2p²q² – 3pq + 4, 5 + 7pq – 3p²q²

Answer: – p2q2 + 4pq + 9 2p2q2 – 3pq + 4, 5 + 7pq – 3p2q2 (2p2q2 – 3pq... View Article

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