Category Archives: Physics Q&A

A car is stopped at a traffic light. It then travels along a straight road such that its distance from the light is given by x(t)=bt^2-ct^3, where b=2.40 m/s^2 and c=0.120 m/s^3. (a) Calculate the average velocity of the car for the time interval t = 0 to t = 10.0 s. (b) Calculate the instantaneous velocity of the car at t=0, t = 5.0 s, and t = 10.0 s. (c) How long after starting from rest is the car again at rest?

This article aims to find a car’s average and instantaneous velocity at times. This article uses the concept of average velocity. Average velocity is the change in position $(Delta x)$ divided by the time intervals $(Delta t)$ in which the displacement occurs. Average velocity can be negative or positive depending on the sign of the shift. […]

A potter’s wheel having a radius of 0.50 m and a moment of inertia of 12 kg m^2 is rotating freely at 50 rev/min. The potter can stop the wheel in 6.0 s by pressing a wet rag against the rim and exerting a radially inward force of 70 N. Find the effective coefficient of kinetic friction between the wheel and the wet rag.

This question aims to find the coefficient of kinetic friction between the wheel and the wet rag. The opposition of any substantial body to its velocity change is defined as inertia. This involves changes in the direction of movement or the speed of the body. The moment of inertia is a quantifiable measure of a body’s rotational inertia, which […]

A hammer in an out-of-tune piano.

This question aims to find the highest and lowest frequency of the string of an out-of-tune piano. The hammer of this piano hits two strings and produces a beat of 7 Hz and one of the strings of this piano is tuned to 131 Hz. The number of waves passing through a fixed point in […]

When the current i is positive, the capacitor charge q is decreasing.

From the given Figure, answer the questions either True or False based on the circuit’s behavior: – After the RELAY is switched to either the N.O. (“normally open”) or N.C. (“normally closed”) state, the transient response of the circuit is for the short time. – In this experiment, the transient current flow has an exponential […]

At one point in a pipeline the water’s speed is 3.00 m/s and the gauge pressure is 5.00 x 10^4 Pa. Find the gauge pressure at a second point in the line, 11.0 m lower than the first, if the pipe diameter at the second point is twice that at the first.

The main objective of this question is to find the gauge pressure at the second point in the pipeline using Bernoulli’s equation. The continuity equation states that the product of the pipe’s cross-sectional area and fluid speed at any instant along the pipe must be constant. This product is equal to the flow rate or […]

The three masses shown in the figure are connected by massless, rigid rods. Find the moment of inertia about an axis that passes through mass A and is perpendicular to the page. Express your answer to two significant figures and include the appropriate units. Find the moment of inertia about an axis that passes through masses B and C. Express your answer to two significant figures and include the appropriate units.

This question aims to find the moment of inertia about the given axis of rotation. Inertia is a property of a body that opposes any force which attempts to move it or to change the magnitude or direction of its velocity if it is in motion. Inertia is a non-resistant property that allows a body to oppose active factors such as forces […]

An object moving in the xy-plane is acted on by a conservative force described by the potential-energy function U(x,y) where ‘a’ is a positive constant. Derive an expression for the force f⃗ expressed in terms of the unit vectors i^ and j^.

[ U(x, y) = a Big( dfrac{1} {x^2} + dfrac{1} {y^2} Big) ] This question aims to find an expression for the Force f which is expressed in terms of the unit vectors i^ and j^. The concepts needed for this question include potential energy function, conservative forces, and unit vectors. Potential Energy Function is a […]

A spring with Spring Constant k=340N/m is used to Weigh a 6.7-kg fish

This question aims to find the change in the length of spring (used to weigh 6.7-kg fish), which is displaced from its mean position. The value of the spring constant is given as k=340N/m. Hooke’s law states that the force exerted by the spring when stretched or compressed from its mean position is directly proportional […]

When a honeybee flies through the air, it develops a charge of +16pC.

Calculate the number of electrons the honeybee loses while it develops the given charge while it flies. The aim of this article is to find the number of electrons being lost by the honeybee while it acquires a positive charge of +16pC as it flies through the air. The basic concept behind this article is the […]

Did the electron move into a region of higher potential or lower potential?

When an electron with an initial speed of $ 6.00 times 10^5 $ m/s, due to an electric field is brought to rest. Find a region i.e., either a higher potential or lower potential that the electron will move. Find the potential difference that is required to stop the electron. Find the initial kinetic energy […]

In an experiment in space, one proton is fixed and other is released from rest (point A), from a distance of 5 mm away. What is the initial acceleration of the proton after it is released?

This question aims to find the initial acceleration of the proton released from a rest point A 5 mm away. The question is based on the concepts of Coulomb’s Law. Coulomb’s law is defined as the electric force between two point charges while they are at rest is called the coulomb’s law. The formula for […]

Calculate the magnitude of the linear momentum for the following cases:

A proton with mass 1.67X10^(-27) kg, moving with a speed 5X10^(6) m/s. A 15.0g bullet moving with a speed of 300m/s. A 75.0 kg sprinter running with a speed of 10.0 m/s. Earth (mass = 5.98X10^(24) kg) moving with an orbital speed equal to 2.98X10^(4) m/s. The aim of this question is to learn the […]

A 2.0 kg piece of wood slides on the surface. The curved sides are perfectly smooth, but the rough horizontal bottom is 30 m long and has a kinetic friction coefficient of 0.20 with the wood. The piece of wood starts from rest 4.0 m above the rough bottom. Where will this wood eventually come to rest?

        From the initial release until the wood reaches the state of rest, what amount of work is done by friction? This problem aims to familiarize with the concepts of dynamic motion which are part of classical dynamic physics. To better understand this topic you should be familiar with kinetic energy, kinetic friction, […]

The current in a 50 mH inductor is known to be

                                                 i  = 120 mA, t<= 0  [ boldsymbol{ i(t) = A_1e^{ -500t } + A_2e^{ -2000t } A, t ge 0 } ] The potential difference across inductor terminals is 3V […]

A cart is driven by a large propeller or fan, which can accelerate or decelerate the cart. The cart starts out at the position x=0m, with an initial velocity of +5m/s and a constant acceleration due to the fan. The direction to the right is positive. The cart reaches a maximum position of x=12.5m, where it begins to travel in the negative direction. Find the acceleration of the cart.

The question aims to find the acceleration of the cart with initial speed vo=5 m.s^(-1). The term acceleration is defined as the rate of change of an object’s velocity with respect to time. Accelerations are normally vector quantities (in that they have magnitude and direction). The orientation of an object’s acceleration is represented by the orientation of the net […]

What is the speed vgas of the exhaust gas relative to the rocket?

A rocket is fired in deep space, where gravity is negligible. In the first second, the rocket ejects $dfrac{1}{160}$ of its mass as exhaust gas and has an acceleration of $16.0$ $dfrac{m^2}{s}$. What is the speed of exhaust gas relative to the rocket? Rockets use propulsion and acceleration to lift off from the ground. Rocket […]

A canoe has a velocity of 0.40 m/s southeast relative to the earth. The canoe is on a river that is flowing 0.50 m/s east relative to the earth. Find the velocity (magnitude and direction) of the canoe relative to the river.

This question aims to find the direction and magnitude of the velocity of the canoe with respect to the river.This question uses the concept of velocity. The velocity of an object has both direction and magnitude.  If the object is moving towards the right, then the direction of velocity is also towards the right. Expert […]

What minimum energy is required to excite a vibration in HCl?

What wavelength of light is required to excite this vibration? The vibration frequency of HCI is $v= 8.85 times 10^{13} space s^{-1}$. This problem aims to familiarize us with vibrating molecules and the energy they dissipate or absorb from their surroundings. This problem requires the core knowledge of chemistry along with molecules and their movements. Let’s […]

The earth’s radius is 6.37×106 m; it rotates once every 24 hours.

Calculate the angular speed of the earth. Calculate the direction (positive or negative) of the angular velocity. Assume you are viewing from a point exactly above the north pole. Calculate the tangential speed of a point on the earth’s surface located on the equator. Calculate the tangential speed of a point on the earth’s surface […]

An astronaut on a distant planet wants to determine its acceleration due to gravity. The astronaut throws a rock straight up with a velocity of + 15 m/s and measures a time of 20.0 s before the rock returns to his hand. What is the acceleration (magnitude and direction) due to gravity on this planet?

This problem aims to find the acceleration due to the gravity of an object on a distant planet. The concepts required to solve this problem are related to gravitational physics, which include Newton’s equations of gravitational motion. A motion under the influence of gravity directs to the vertical movement of an object whose motion is […]

A spherical interplanetary probe of 0.5m diameter contains electronics that dissipates 150 W. If the probe surface has an emissivity of 0.8 and the probe does not receive radiation from other surfaces, as, for example, from the sun, what is its surface temperature?

This article aims to find the surface temperature. According to Stefan Boltzmann’s law, the amount of radiation emitted per unit time from region $A$ of a black body at absolute temperature represented by $T$ is directly proportional to the fourth power of temperature. [dfrac{u}{A}=sigma T^{4}] where $sigma$ is the Stefan constant $sigma=5.67 times 10^{-8} dfrac{W}{m^{2}. {K}^{4}}$ is derived from other […]

Boxes A and B are in contact on a horizontal friction-less surface. Box A has mass 20 kg and box B has mass 5kg.A horizontal force of 250N is exerted on box A. What is the magnitude of the force that box A exerts on box B?

This problem aims to familiarize us with a friction-less motion between two masses as a single system. The concept required to solve this problem includes acceleration, newtons law of motion, and the law of conservation of momentum. In this particular problem, we require the help of newton’s second law, which is a quantitative definition of […]

Calculate the frequency of each of the following wavelengths of electromagnetic radiation.

$632.8, nm$ (wavelength of red light from a helium-neon laser). Express your answer using three significant figures. $503, nm$ (wavelength of maximum solar radiation). Express your answer using three significant figures. $0.0520, nm$ (a wavelength contained in medical X-rays). Express your answer using three significant figures. In this question,  wavelengths of different types of electromagnetic […]

Water is pumped from a lower reservoir to a higher reservoir by a pump that provides 20 kW of shaft power. The free surface of the upper reservoir is 45 m higher than that of the lower reservoir. If the flow rate of water is measured to be 0.03 m^3/s, determine mechanical power that is converted to thermal energy during this process due to frictional effects.

The main objective of this question is to find the mechanical power converted to thermal energy during the given process. Mechanical energy is the energy that an object possesses as a result of its motion or position. Mechanical energy is classified into two types, that is potential energy and kinetic energy. The potential energy refers to […]