In a particle accelerator, you accelerate an electron. Afterwards, you measure it's energy to be 350 keV. Tell my why you can't find the speed from this energy using your knowledge of classical mechanics.
In order to see what the problem is, I will attempt to find this speed. 350keV=5.6110-14 J Ek=1/2 * mv2 => v=sqrt(2Ek/m) By plugging in numbers, we find that the velocity of the electron, v=3.51108. This velocity is bigger then the speed of light c=3108, and it is a known fact that nothing can travel faster than light. This means that relativistic effects must've taken place, which prevented the particle from reaching the speed of light, but allowed it to have such a high energy.
CP
Related Physics A Level answers
All answers ▸In an electric propulsion system, alpha particles are accelerated through a potential difference of 100kV at an average rate of 10^20 alpha particles per second. Calculate the average thrust the system can provide.
If a bulb has a current of 20mA and voltage of 5V, and the current cost of electricity is £3 for a kW/hour. How much money would you spend to power the bulb for 8 hours? Are these good estimates for the current, voltage and cost of electricity?
A projectile is fired at an angle of 30 degrees from the horizontal, it reaches a maximum height of 12m above the ground before coming to rest 600m from its initial starting point at the same level. What is the initial speed of the projectile?
Using Newton's law of universal gravitation, show that T^2 is proportional to r^3 (where T is the orbital period of a planet around a star, and r is the distance between them).