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The gravitational force between two objects is F. If masses of both the objects are halved without altering the distance between them, then the gravitational force would become:

If we cover half of a concave mirror, the image size will

During the night, distant sounds become louder than during the day. This is due to:

A body is moving vertically upwards.Its velocity changes at a constant rate from $50m{s}^{-1}$ to $20m{s}^{-1}$ in 3s.What is its acceleration?

Penguins huddling: To withstand the harsh weather of the Antarctic, emperor penguins huddle in groups. Assume that a penguin is a circular cylinder with a top surface area a =0.26 $m^2$ and height h = 90 cm. Let $P_r$ be the rate at which an individual penguin radiates energy to the environment (through the top and the sides); thus $N{P}_r$ is the rate at which N identical, well-separated penguins radiate. If the penguins huddle closely to form a huddled cylinder with top surface area Na and height h, the cylinder radiates at the rate $P_h$. If N = 1000, by what percentage does huddling reduce the total radiation loss?

A rocket with an initial mass of $1000\text{kg}$ is launched vertically upwards from rest, under gravity. The rocket burns fuel at the rate of $10\text{kg/sec}$. The burnt matter is ejected vertically downwards with speed of $2000{\text{ms}}^{-1}$ relative to rocket. If the burning stops after one minute, find the maximum velocity of the rocket.

[Take $g=10{\text{m/s}}^2,\ln \left(2.5\right)=0.92$]

A bus running at a speed of 18 km/h is stopped in 2.5 seconds by applying brakes. Calculate the retardation produced.

Distinguish between:

(1) Force and momentum.

(2) Inertia of motion and inertia of direction

(3) Inertia of motion and inertia of rest.

A goalkeeper in a game of football pulls his hands backward after holding the ball shot at the goal. This enables the goalkeeper to

A shot travelling at the rate of 100 m/s is just able to pierce a plank 4 cm thick. What velocity is required to just pierce a plank 9 cm thick?

A weightlifter lifted a load of 200 kgf to a height of 2.5m in 5s .Calculate :

1-the work done

2-the power developed by him

Take g=10N 1/kg

Identify the correct position of the image of the Sun formed by the concave mirror.

A toy car is powered by water and compressed air. When the car is fully pumped up and released, it accelerates at $2\frac{m}{s^2}$ for 3 seconds. As soon as this water runs out the car begins to slow down. The car travels a combined total of 27 meters before coming to rest. What is its rate of acceleration when stopping and what is the total time of the motion?

Two cylindrical vessels fitted with pistons A and B of area of cross section 8 $c{m}^2$ and 320 $c{m}^2$ respectively, are joined at their bottom by a tube and they are completely filled with water. When a mass of 4 kg is placed on piston A, find : (i) the pressure on piston A, (ii) the pressure on piston B, and (iii) the thrust on piston B.

A man hits a table with a flat stick applying a force of $20N$. If the area over which the force is acting is $2c{m}^2$, calculate the pressure on that area.

An aeroplane takes off at an angle of 60^{​​​​​​°}to the horizontal. If the velocity of the plane is 200km/hr , calculate its horizontal and vertical component of its velocity.

In which of the following, the image of an object placed at infinity will be highly diminished and point sized?

A front end loader applied a force of 150 N to move a rock such that 1250 J of work is done. How far is the rock moved?

A travelling wave pulse is given by equation,

$y=\frac{4}{3x^2+48t^2+24xt+2}$, where $x$ and $y$ are in metre and $t$ is in second. The wave velocity is

The reflection of the parallel rays of a torch light can be seen by only one observer. Why? [3 MARKS]

Which one of these quantities is not related with Newton's second law of motion?

Car A is fitted with a convex mirror of focal length 20 cm. Car B is 6 meters behind the car A. Find the position of the car B when seen from the mirror of car A.

The force due to the magnetic field on a current carrying conductor is _______ to the magnetic field and_________ to the current.

Milk has a density of 1.25 g/ml, calculate the mass of 1 l of milk.

Find the time for which a force of 1kgwt acts on a body of mass 1 kg moving with a uniform speed of 4m/s to stop the body.

The image of a clock as seen in a mirror is shown here. If the clock shows correct time at this instance but starts losing 1 minute every hour after this, which of the following depicts the correct picture of the clock after 10 hours?

Question 2 (ii)
Write the coordinates of C.

Match the entries of column I with the entries of column II in the following table.

Column I	Column II
$\left(A\right)$	$\left(P\right)$ Wires $1$ and $2$ attract each other.
$\left(B\right)$	$\left(Q\right)$ Wires $1$ and $2$ do not exert any force on each other.
$\left(C\right)$	$\left(R\right)$ Magnetic fields at point $P$ due to wires $1$ and $2$ are perpendicular to each other.
$\left(D\right)$ Wires $1$ and $2$ are in the same plane without touching each other.	$\left(S\right)$ Magnetic fields at point $P$ due to wires $1$ and $2$ are in the same direction.