Physics

Thrust depends on the rate of ejected gases and their velocity. In the absence of gravitational force, thrust is constant only if the rate of ejected gases remains constant. Otherwise, thrust varies.

The force exerted by water striking a wall normally can be calculated using the momentum principle: Force = mass flow rate × change in velocity. The mass flow rate is density × discharge = 1000 kg/m³ × 0.0001 m³/s = 0.1 kg/s. Since the water velocity changes from 10 m/s to 0 upon striking the wall, the force is 0.1 kg/s × 10 m/s = 1 N. This matches option A. The original question had the correct calculation in the explanation but incorrectly stated the correct answer as B (10 N). The verified correct answer is A (1 N).

When the stretching force T on a wire increases, the tension in the wire increases, which raises the wave speed along the wire. Since frequency is directly proportional to wave speed for a fixed length, the frequency increases.

In a Michelson Interferometer, moving one mirror by a distance d changes the optical path length by 2d because the light travels to the mirror and back. Each fringe observed corresponds to a change in path length equal to one wavelength λ. Therefore, the number of fringes m observed when the mirror moves by d is given by m = 2d / λ. Given d = 0.5 mm = 500,000 nm and m = 2000 fringes, the wavelength λ = 2d / m = (2 × 500,000 nm) / 2000 = 500 nm. Since 1 nm = 10 Å, 500 nm = 5000 Å. Among the options, 5000 Å (option B) correctly represents the wavelength of the light used. Option A (5000 nm) is incorrect as it is 10 times larger than the correct value. Options C and D are not relevant units for wavelength in this context.

In a closed pipe, the closed end is a displacement node because the air molecules cannot move freely there, causing a node in the stationary wave. This is a fundamental concept in wave physics related to standing waves in air columns.

A resistance is deliberately introduced in series in a circuit primarily to control the current flowing through the circuit. While it does decrease current, the main purpose is to regulate or control it to desired levels, making option C the most accurate answer.

Sound waves involve rapid compressions and rarefactions that occur too quickly for heat exchange, so the process is adiabatic rather than isothermal or isochoric. Therefore, the pressure and volume changes in sound waves follow the adiabatic law.

When an athlete runs before jumping, they increase their velocity, which increases their momentum (momentum = mass × velocity). This greater momentum helps them jump farther.

The number of beats produced per second is equal to the absolute difference between the frequencies of two tuning forks. This difference causes the interference pattern perceived as beats.

When bulbs rated for the same voltage are connected in series, the bulb with the lowest power rating has the highest resistance and thus drops more voltage, causing it to glow more brightly compared to the others. Therefore, the 40 W bulb will burn most brightly.