Physics Crisis?! 10 pts!?

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Physics Crisis?! 10 pts!?



I need to check if I had gotten these correct before I turn it in. The grades count a lot! Explanation would also be great too! I am desperately in need of help! Any questions would be great! 

1) [Use e = 1.6 × 10-19 C] 

An electron in a uniform electric field experiences a force of 6.4 *10^-15 N. What is the strength of the field? 

2) An object of mass 1.8 *10^-5 kg carries a charge of 9.0 *10^-9 C. If the object is only influenced by a uniform electric field of 36000 N/C, what acceleration does the object have?

3) An object of mass m and carrying a charge q exists in an electric field E. Write an expression for the object s acceleration. 

4) [Use k = 9 × 109 N m2/C2] 

What is the magnitude of the electric field 1 cm from a 3 nC charge? 

5) Consider a particle with a charge of 0.004 C. In order to move the particle from the origin to a point 1.6 meters away, an external agent must do 16 J of work on the particle. What is the potential difference between the initial and final positions of the particle? 

6) A positive charge of 0.15 C moves through an electric field, going from a potential of +5 volts to -5 volts. How much work does the electric field do on the charge? 

7) A particle of mass 2.0 *10^-18 kg and charge 1.0 *10^-14 C is initially at rest. The charge is accelerated by a potential difference of 90000 volts. What is the final speed of the particle?



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Posted Answers:

1) 
F = Q*E 
E = 4.0×10^4 N/C 

2) 
a = F/m = Q*E/m = 18 m/s^2 

3) 
This should come before 12) maybe lol? 
a = Q*E/m 

4) 
E for a point charge = kQ/r^2 = 2.7×10^5 N/C 

5) 
W = Q*U where U is difference in potential (voltage) 
U = 4000 V 

6) 
0.15 C * 10 V = 1.5 J 

7) 
W = Q*U = 9×10^-9 J 
Work done is equal to the final kinetic energy of the particle if it was initially at rest. 
W = 0.5m*v^2 
v = 3.0×10^4 m/s