Search our library of Physics questions

Top answers

Physics

All levels

A car of mass 1000 kg is travelling at 20 (m/s). The car crashes into a tree, and comes to a complete halt in 0.05s. Calculate the force acting on the car during the collision.

We are asked for the force acting on the car and we know from Newton's second law that F = ma Therefore, we need to calculate the acceleration first. We use a = (vf - vo)/(t - to) where vf = final speed, ...

Answered by Pablo M. • Physics tutor

2547 Views

What are the differences between sound waves and electromagnetic waves?

Propagation:
Sound waves are longitudinal, meaning that the vibrations occur parallel to the direction of propagation (travel).

Electromagnetic wa...

Answered by Wendy L. • Physics tutor

47611 Views

Explain the photo-electric effect and describe how the intensity of light effects rate of electron emission.

The photo-electric effect is the way in which electrons are released from the surface of a metal when there is an incident light ray. The particle model of light, as part of wave-particle duality, suggest...

Answered by Ira W. • Physics tutor

2517 Views

Calculate the resistance of a uniform wire of diameter 0.5mm, length 2m and resistivity 1.7x10^-8Ωm.

R=ρ L/AR= (1.7*10^-8 2)/(0.0005^2π/4)R=0.173Ω

Answered by Heather W. • Physics tutor

1810 Views

Explain the input and output energy sources for a car engine. How would you calculate the efficiency? Explain in terms of the inputs and outputs how the efficiency could be improved.

The input is chemical energy (in the form of fuel). The outputs areSound (not useful)Kinetic (useful)Heat (may be useful)The efficieny is given by useful output energy divided by total input (or output) e...

Answered by Samuel H. • Physics tutor

14850 Views