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A rod of weight $w$ is supported by two parallel knife edges A and B and is in equilibrium in a horizontal position. The knives are at a distance $d$ from each other. The centre of mass of the rod is at distance $x$ from A. The normal reaction on A is:
A body cools from a temperature $3T$ to $2T$ in $10\text{ minutes}$. The room temperature is $T$. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next $10\text{ minutes}$ will be:
A force vector applied on a mass is represented as $\vec{F} = 6\hat{i} - 8\hat{j} + 10\hat{k}$ and accelerates with $1 \text{ m/s}^2$. What will be the mass of the body?
Two persons of mass $55 \text{ kg}$ and $65 \text{ kg}$ respectively, are at the opposite ends of a boat. The length of the boat is $3.0 \text{ m}$ and weighs $100 \text{ kg}$. The $55 \text{ kg}$ man walks up to the $65 \text{ kg}$ man and sits with him. If the boat is in still water the centre of mass of the system shifts by:
A spherical black body with a radius of $12\text{ cm}$ radiates $450\text{ W}$ power at $500\text{ K}$. If the radius were halved and the temperature doubled, the power radiated in watts would be:
A man of mass 80 kg is standing in an elevator which is moving with an acceleration of 6 m/s² in the upward direction. The apparent weight of the man will be (g = 10 m/s²):
The average force necessary to stop a bullet of mass 20 g moving with a speed of 250 m/s, as it penetrates into the wood for a distance of 12 cm is:
Two objects of mass $10 \text{ kg}$ and $20 \text{ kg}$ respectively are connected to the two ends of a rigid rod of length $10 \text{ m}$ with negligible mass. The distance of the center of mass of the system from the $10 \text{ kg}$ mass is:
The quantities of heat required to raise the temperature of two solid copper spheres of radii $r_1$ and $r_2$ ($r_1=1.5 r_2$) through $1\text{ K}$ are in the ratio:
A satellite in force-free space sweeps stationary interplanetary dust at a rate dM/dt = αv, where M is the mass, v is the velocity of the satellite, and α is a constant. What is the deceleration of the satellite?
A ball of mass 0.5 kg moving with a velocity of 2 m/s strikes a wall normally and bounces back with the same speed. If the time of contact between the ball and the wall is one millisecond, the average force exerted by the wall on the ball is:
A uniform rod of length $200 \text{ cm}$ and mass $500 \text{ g}$ is balanced on a wedge placed at $40 \text{ cm}$ mark. A mass of $2 \text{ kg}$ is suspended from the rod at $20 \text{ cm}$ and another unknown mass $m$ is suspended from the rod at $160 \text{ cm}$ mark as shown in the figure. What would be the value of $m$ such that the rod is in equilibrium? (Take $g=10 \text{ m/s}^2$)
A piece of iron is heated in a flame. It first becomes dull red then becomes reddish yellow and finally turns to white hot. The correct explanation for the above observation is possible by using
Rocket engines lift a rocket from the earth surface because hot gases with high velocity:
A 500 kg car takes a round turn of radius 50 m with a velocity of 36 km/hr. The centripetal force is:
A particle moves in a circular orbit under the action of a central attractive force inversely proportional to the distance $r$. The speed of the particle is:
When a uranium isotope $^{235}_{92}\text{U}$ is bombarded with a neutron, it generates $^{89}_{36}\text{Kr}$, three neutrons and :
The total radiant energy per unit area per unit time, normal to the direction of incidence, received at a distance $R$ from the centre of a star of radius $r$, whose outer surface radiates as a black body at a temperature $T\text{ K}$ is given by (where $\sigma$ is Stefan's constant):
In an elevator moving vertically up with an acceleration $g$, the force exerted on the floor by a passenger of mass $M$ is:
Thermodynamic processes are indicated in the following diagram. Match the following: **Column-I** (P) Process I (Q) Process II (R) Process III (S) Process IV **Column-II** (a) Adiabatic (b) Isobaric (c) Isochoric (d) Isothermal