Q47P - Fundamentals Of Physics

Question

Question: Beams of high-speed protons can be produced in “guns” using electric fields to accelerate the protons. (a) What acceleration would a proton experience if the gun’s electric field were $2.00\times {10}^4 N/C$ ? (b) What speed would the proton attain if the field accelerated the proton through a distance of 1.00 cm?

Step-by-Step Solution

Answer

• a) The acceleration that the proton experiences is $1.92\times {10}^{12} m/s^2$
• b) The speed of the proton is $1.96\times {10}^5 m/s^2$

Step 1: The given data

• a) Electric field of the proton,$E=2\times {10}^4 N/C$
• b) The initial speed of the electron,$V_0=0 m/s$
• c) Distance by which proton travels,$x =1 cm$

Step 2: Understanding the concept of electric field and the kinematics

Using the concept of Newton's second law and the relation of force to the electric field, we can get the acceleration of the proton. Again, using the equation of kinematics, we can get the speed of the proton.

Formulae:

The force on a body due to Newton’s second law, $F = ma$  (i)

The force and the electric field relation,   F = qE                  (ii)

The third equation of kinematics,$V^2=V_0^2+2ax$                    (iii)

Step 3: a) Calculation of the acceleration of the proton

Using the given data and equation (ii) in equation (i), we can get the acceleration of the proton as follows:

$$\begin{gathered} a =\frac{eE}{m} \\ =\frac{\left(1.60\times {10}^{-19}C\right)\left(2.00\times {10}^4 N/C\right)}{\left(1.67\times {10}^{-27}kg\right)} \\ =1.92\times {10}^{12} m/s^2 \end{gathered}$$

Hence, the value of the acceleration is $1.92\times {10}^{12} m/s^2$

Step 4: b) Calculation of the speed of the proton

Using the given data and the value of acceleration in equation (iii), the speed of the proton is given as:
$$\begin{gathered} v=\sqrt{2ax} \\ =\sqrt{2\left(1.92\times {10}^{12} m/s^2\right)\left(0.0100 m\right)} \\ =1.96\times {10}^5 m/s^2 \end{gathered}$$

Hence, the value of the speed of the proton is.$1.96\times {10}^5 m/s^2$