Positrons are antimatter versions of electron with mass m_e = 9.11 times 10^-31
ID: 1655933 • Letter: P
Question
Positrons are antimatter versions of electron with mass m_e = 9.11 times 10^-31 kg. Consider a linear particle accelerator which uses an electric field to accelerate a positron down its length, parallel to the ground. The accelerator is 196 m long and exerts a uniform force of 6.17 fN (femtonewtons) on the positron during its acceleration. How long does it take to leave the accelerator if the positron starts at rest? Ignore all other forces apart from the acceleration force and express your answer in seconds. Note that you enter express numbers in scientific notation into the system using engineering notation so that 9.11 times 10^-31 is expressed as 9.11 e-31. Answer: Consider a carefully stacked, perfectly vertical column of 200 loonies, each of which has a mass of m = 6.27 g. Resist the temptation to push the stack over "just to see what happens" (that's later in the course!). Instead, calculate the upward force exerted by the 26th coin in the stack on the 27th coin (counting such that the bottom coin is #1, the next coin in the stack is #2, etc.). Express your answer in Newtons. Answer:Explanation / Answer
4. for the given positron
mass = m = 9.1*10^-31 kg
charge, q = 1.6*10^-19 C
length of accelerator, l = 196 m
Force, F = 6.17 fn = 6.17*10^-15 n
acceleration = F/m = 6.78*10^15 m/s/s
so, initial velocity = 0
hence l = 0.5at^2
t = sqrt(2l/a)
t = 2.4044*10^-7 s
hence the particel takes 2.4044e^-7 s to leave the accelerator