Physics Questions & Answers - Physics Doubts, Problems, Homework Solutions

A 25 micro farad is charged until the potential difference across it is 500V. Calculate the charge stored at this moment.

The formula to be used here is C = Q / V. Where C = capacitance, Q = charge and V = potential difference. First we can put in the …

Why does time slow down for someone standing at the bottom of a mountain compared to time for someone at the top of a mountain?

The concept of time is influenced by the force of gravity. On a planet, gravity acts on every object within its gravitational field. The closer the object is to the …

What is a boson, as described by the standard model?

A boson is a "force-carrier": a particle that corresponds to one of the fundamental forces of nature. There are four fundamental forces, which include: Gravity, Electromagnetism, Weak Nuclear Force and …

An internet shopping company is planning to use drones to deliver packages.During a test the drone is hovering at a constant height above the ground.The mass of the drone is 5·50 kg. The mass of the package is 1·25 kg. See questions below

a) Determine the upward force produced by the droneWe can simplify the problem by drawing a free body diagram. This allows us to analyse the forces involved. We are told …

Two cables hold a mass of 100kg, joining in the middle of the top of the mass. Two helicopters lift a cable each and hover so that the height of the mass is constant. Each cable makes an angle of 57° with the normal. Find the tension in each cable.

Once you note that the height is constant, the key thing to remember here is that there is no unbalanced force acting on the mass. By this, I mean that …

An exoplanet, 0.01% the mass of the Sun, orbits a star 2 times the mass of the Sun at a distance of 1AU = 1.5x10^8 km. Using Newton's Law of Universal Gravitation, determine the force between the exoplanet and the star. Mass of Sun = 2x10^30kg.

This question is not particularly tricky as long as it is read carefully.
First, calculate the masses of the Star and the Exoplanet. Double the mass to find the star …

Explain the difference between elastic and inelastic collisions.

In all collisions, provided there are no external forces, momentum is conserved. This is the law of conservation of momentum. However, kinetic energy is not conserved in all collisions. An …

An exoplanet of mass 1.36x10^26 kg is orbiting a star of mass 3.2x10^31 kg at a distance of 1 AU. What is the magnitude of the gravitational force between the two?

We use Newtons equation for gravitational force. F=GMm/r².1 AU is the mean distance at which the Earth orbits the Sun, taken to be: 1.49x10¹¹ m.Substituting in the …

In a lab a hydrogen spectral line is observed to have a wavelength of 656nm. This line is observed in a distance galaxy to have a wavelength of 661nm, what is the recessional velocity of the galaxy?

This question is dealing with phenomena of Redshift, where wavelengths are shifted due to movement between observer and event. The key information to extract from the question is we have …

A launcher 1m tall fires tennis balls with a velocity of 15m/s at an angle of 20 degrees from horizontal. Neglecting air resistance, calculate the maximum height, time of flight and distance traveled by the ball.

While conceptually simple, drawing on understanding of kinematic equations and vectors, these projectile problems require attention to the details of the problem such as accounting for the launch height and …

A drone is hovering at a constant height above the ground. The mass of the drone is 7 kg. The mass of the package is 3 kg. Calculate the upward force of the Drone.

To answer this Question we will use the equation derived from Newtons second law of motion,
F=ma or in this case W=mg as it is the mass of the object …

A golf ball is hit at an angle θ=45° to the horizontal with an initial speed v0. A vertical wall of height h=10m lies a distance d=20m away. Determine the minimum initial speed v0 required for the ball to clear the wall. Air resistance is negligible.

(I have a picture of a full explanation saved on my computer and I can show this or recreate using the whiteboard during interview if required.)
Physics: Newton's 2nd …

A tall 2 meter tall basketball player shoots for the net that stands 3 meters from the ground. If he throws he ball from head height at an angle of 60 degrees and the ball travels at 10 meters per second, how far away is the hoop?

By taking the initial vertical speed as v_v = 6 sin(60) = 5.2 ms^-1.The max height of the ball is given by v_v² = u …

A photon of wavelength 656.3nm is emitted in the Balmer series of a Hydrogen emission lamp. (a). Show that the frequency of the photon is 4.57*10^14 Hz. (b).Use the Planck-Einstein relationship to calculate the energy of the photon.

(a). Firstly, pull out useful information . λ=656.3nm Secondly, identify relevant equation and rearrange to find frequency. λ=c/f => f=c/λ Calculate frequency using the given values (c=310^8 m/s), ensuring …

Calculate the gravitational force acting on the Moon, caused by the Earth, given that the masses of the Earth and the Moon are 6 x10^24 and 7.3 x10^22, respectively. The distance between the Earth and the Moon is 384 400 km.

The relevant equation to use in solving this problem, from Newton's law of gravitation, is Force = ( universal constant of gravitation x mass of earth x mass of moon)/ …

A circuit with a cell of voltage 6V and two resistors of resistance 6 Ohms each connected in parallel. What is the current through the Cell?

Step 1 - draw the circuit.
Step 2- Finding total resistance of resistors in parallel, 1/Rt = 1/R1 + 1/R2 where Rt is the total resistance of the circuit.
Step …

If a footballer kicks a ball straight down the pitch at 6 ms-1 at an angle θ of 30° above the horizontal, what is the maximum height reached by the ball?

First we must remember our equations of motion, (SUVAT equations).S = Displacement U = Initial velocity V = Final velocity A = Acceleration T = TimeV = U + A …