Search our library of Physics A Level questions

Top answers

Physics

A Level

What is Newtons third law of motion?

To every action, there is always an equal and opposite reaction.Force always occurs in pairs. Consider two bodies A and B, force on a body A by B is equal and opposite to the force on the body B by A.i.e,...

Answered by Subin B. • Physics tutor

1584 Views

Calculate the threshold wavelength for a metal surface with work function of 6.2 eV.

threshold wavelength where photoelectrons have no energy, i.e. Work function = hc/wavelength.Rearrange for wavelength and substitute. Wavelength = 2*10^-7 m.

Answered by Daniel P. • Physics tutor

13916 Views

Explain why objects in free fall drop to the ground at the same speed, regardless of their mass.

An object in free fall is only subject to the gravitational force from the earth. The magnitude of this force is mg, where m is the mass of the object. Newton's second law states that the force on an obje...

Answered by James G. • Physics tutor

1548 Views

Calculate the root mean squared speed for 16g of oxygen gas at 50(deg Celsius) and explain why we use this instead of the average velocity of all the particles.

Root mean squared speed is given by v(rms) = (3kbT/m)^(0.5) = 501.68. Student should show how to calculate the mass of each particle (m = (0.016)/0.5(6.01x10^23)), convert degrees celsius into kelvin and ...

Answered by Jonathan W. • Physics tutor

1405 Views

A car of mass m travelling with a velocity v comes to rest over a distance d in time t. The constant frictional force acting on the car while it is braking is found using:

Newton's Second Law: F=maa=v-u/tUsing SUVAT equations: v²= u²+2asv (final velocity)=0 u(inital velocity)= v s=d Rearranging gives: -v²=2ad a=-v²/2d Therefore F=...

Answered by Ghafoor H. • Physics tutor

6725 Views