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A proton accelerates from rest in a uniform electric field of 635 N/C. At some time later, its speed is 1.30 × 106 m/s. What is the magnitude of its acceleration? The mass of a proton is 1.6726 × 10−27 kg and the fundamental charge is 1.602 × 10−19 C . Answer in units of m/s 2 . 031 (part 2 of 4) 10.0 points How long does it take the proton to reach this speed? Answer in units of s. 032 (part 3 of 4) 10.0 points How far has it moved in this time interval? Answer in units of m. 033 (part 4 of 4) 10.0 points What is its kinetic energy

1 Answer

5 votes

1)
6.11\cdot 10^(10) m/s^2

The force experienced by the proton is


F=qE

where


q=1.6\cdot 10^(-19)C is the proton charge


E=635 N/C is the strength of the electric field

Substituting into the equation,


F=(1.6\cdot 10^(-19) C)(635 N/C)=1.02\cdot 10^(-16)N

The acceleration of the proton is given by Newton's second law:


a=(F)/(m)

where


F=1.02\cdot 10^(-16)N is the force exerted on the proton


m=1.67\cdot 10^(-27) kg is the proton's mass

Substituting,


a=(1.02\cdot 10^(-16)N)/(1.67\cdot 10^(-27)kg)=6.11\cdot 10^(10) m/s^2

2)
2.13\cdot 10^(-5) s

We can use the following equation:


a=(v-u)/(t)

where


a=6.11\cdot 10^(10) m/s^2 is the acceleration of the proton


v=1.30\cdot 10^6 m/s is the final velocity

u = 0 is the initial velocity

t is the time

Solving the equation for t, we find


t=(v-u)/(a)=(1.30\cdot 10^6 m/s -0)/(6.11\cdot 10^(10) m/s^2)=2.13\cdot 10^(-5) s

3) 13.86 m

The distance travelled by the proton is given by the equation


d=ut + (1)/(2)at^2

where

u = 0 is the initial velocity


t=2.13\cdot 10^(-5) s s the time


a=6.11\cdot 10^(10) m/s^2 is the acceleration of the proton

Substituting,


d=0 + (1)/(2)(6.11\cdot 10^(10)m/s^2)(2.13\cdot 10^(-5) s)^2=13.86 m

4)
1.41\cdot 10^(-15) J

The final kinetic energy of the proton is given by


K=(1)/(2)mv^2

where we have


m=1.67\cdot 10^(-27) kg is the proton's mass


v=1.30\cdot 10^6 m/s is the final velocity

Substituting into the formula,


K=(1)/(2)(1.67\cdot 10^(-27)kg)(1.30\cdot 10^6 m/s)^2=1.41\cdot 10^(-15) J

User Aleksandr Erokhin
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