Electric Potential and Potential Energy (Uniform Fields) The potential difference ∆V needed to stop a moving charged particle is called the “stopping potential.” Suppose a proton is moving in the +x direction with an initial speed of 7.1 x 106 m/s. Assume the electric force is the only relevant force in this problem. a) Find the stopping potential necessary to bring the proton to rest. b) In which direction is the electric field pointing in order to slow the proton down? c) At the initial position of the proton, the electric potential is 220,000 Volts (220 kilovolts or kV). What is the electric potential at the position where the proton comes to rest? d) Would an electron traveling at the same speed requires greater or lesser magnitude stopping potential? Explain your answer (hint: do an electron and proton moving at the same speed have the same kinetic energy?).

........

An electron is initially at ground level, and the electric potential at that point is assumed to be exactly zero. The electron is immersed in a uniform electric field that points down with a magnitude of 4.4 x 10-11 N/C as well as Earth’s gravitational field (9.8 N/kg, pointing down). Only gravity and the electric force have any effect in this problem. a) If the electron is given an initial upward velocity of 36 m/s, to what maximum height above ground level does it reach? b) What is the change in electric potential energy (final - initial) during this motion? c) How much work is done by the electric force during this motion? d) What is the voltage at the electron’s maximum height?

.

.

.

will vote, please show work and signs

1.The Celestar 8 telescope available in the Physics Lab is described on Blackboard. The primary mirror of a Celestar 8 has an aperture of 203 mm, and the secondary mirror that blocks the primary mirror has a diameter of 70 mm. The focal length of the primary mirror is 2032 mm. Using this information calculate the following:

a) [2 marks] The fraction of the incoming light blocked by the secondary mirror.

b) [3 marks] The light gathering power of the Celestar 8 telescope, relative to the human eye with a pupil size of 7 mm, in each of these cases: i) Taking into account that the secondary mirror blocks some of the incoming light. ii) Ignoring the blockage of light by the secondary mirror.

c) [2 marks] The resolution of the telescope under ideal conditions (no air turbulence) measured in seconds of arc. Assume that you are observing with the visible wavelength of 550 nm.

d) [2 marks] The diameter, in metres, of the smallest crater that you can observe on the Moon’s surface with the Celestar 8 telescope, assuming ideal seeing conditions (no atmospheric turbulence), visible light with wavelength 550 nm, and the distance to the Moon found on the course formula sheet.

e) [1 mark] The magnification of the Celestar 8 telescope if a 15 mm focal length eyepiece is used.

A 1220-kg car pulls a 390-kg trailer. The car exerts a horizontal force of 3.6 × 10³ N against the ground in order to accelerate.

What force does the car exert on the trailer? Assume an effective friction coefficient of 0.19 for the trailer.

(Express your answer to two significant figures and include the appropriate units.)

A 7800 kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.15 m/s2 and feels no appreciable air resistance. When it has reached a height of 575 m , its engines suddenly fail so that the only force acting on it is now gravity. A) What is the maximum height this rocket will reach above the launch pad? b)How much time after engine failure will elapse before the rocket comes crashing down to the launch pad? c)How fast will it be moving just before it crashes?

Beginning with the Weizsäcker semi-empirical mass formula, show that the minimum in a mass parabola occurs at a value of atomic number, Zmin, given by

Note: The Weizsäcker semi-empirical mass formula for the binding energy, B, of a nucleus is where A is the atomic mass number of the nucleus and Z is the atomic number of the nucleus. Hint: Although atomic number, Z, only takes integer values, assume it is a continuous variable for the purpose of this exercise.

The expression for atomic mass, m, at the bottom of Page 4/10 of the lecture notes can then be regarded as a quadratic function of Z.

Take ¶m/¶Z, the partial derivative of the expression as a function of Z. ¶m/¶Z is zero at the minimum value of m. Therefore, setting ¶m/¶Z to zero and solving for Z gives you Zmin. Zmin = mn −m p ( −me )c2 +aC A−1/3 +4asym 2aC A−1/3 +8asym A−1 B=+ aV A − aS A2/3 − aC Z(Z −1) A1/3 − asym (A−2Z ) 2 A −aP 1 A3/4

QUESTION 1

1. If the metallic ball is launched at an angle of 25° above the horizontal at a speed of 14 m/s. The ball returns to level ground. Which combination of changes must produce an increase in time of flight of a second launch?

   		decrease the launch angle and decrease the ball’s initial speed
   		increase the launch angle and decrease the ball’s initial speed
   		decrease the launch angle and increase the ball’s initial speed
   		increase the launch angle and increase the ball’s initial speed

10.00000 points   

QUESTION 2

1. If the metallic ball is thrown vertically upward into the air. What is the instantaneous acceleration of the ball at its highest point?   

   		changing from 9.8 m/s2 up to 9.8 m/s2 down
   		9.8 m/s2 up.
   		9.8 m/s2 down.
   		zero.

10.00000 points   

QUESTION 3

1. A projectile is fired with an initial velocity of 120.0 m/s at an angle, θ, above the horizontal. If the projectile’s initial horizontal speed is 55 meters per second, then angle θ measures approximately

   		13°
   		27°
   		63°
   		75°

10.00000 points   

QUESTION 4

1. If the metallic ball is propelled with an initial velocity of 60. m/s at 37° above the horizontal. The horizontal component of the golf ball’s initial velocity is

   		30. m/s
   		40 m/s
   		48 m/s
   		36 m/s

10.00000 points   

QUESTION 5

1. A projectile is thrown with an initial velocity of 100 m/s north is given an acceleration of 10 m/s2 south. What will its velocity be after 6.0 s?
   

   		60 m/s north
   		40 m/s north
   		40 m/s south
   		60 m/s south

10.00000 points   

QUESTION 6

1. A projectile is fired at an angle of 45° above the horizontal. Assume that air resistance is not significant. While the projectile is in flight, the acceleration…….

   		increases
   		decreases
   		is maximum
   		is constant

10.00000 points   

QUESTION 7

1. If the metallic ball is shot with an initial velocity of 10 meters per second at an angle of 30.° above the horizontal. The magnitude of the horizontal component of the ball’s initial velocity is

   		9.8 m/s
   		8.7 m/s
   		5.0 m/s
   		10 m/s

10.00000 points   

QUESTION 8

1. If the metallic ball is thrown straight down with an initial velocity of 50 m/s. (g = 10 m/s2 down). After 2.0 s the magnitude of its velocity is:

   		70  m/s
   		62  m/s
   		110 m/s
   		30  m/s
   		2.5 m/s

A(n) 7.8-kg object is sliding across the ice at2.34 m/s in the positive x direction. An internal explosion occurs, splitting the object into two equal chunks and adding 12 J of kinetic energy to system. The explosive separation takes place over a 0.16-s time interval. Assume that the one of the chunks after explosion moves in the positive xdirection. The x component of the average acceleration of this chunk during the explosion is afrontx, the x component fo the average acceleration of the other chunk during the explosion is arearx.

What are the x components of the average accelerations of the two chunks during the explosion?

Enter your answers numerically separated by a comma.

Two point charges totaling 9.00 µC exert a repulsive force of 0.200 N on one another when separated by 0.712 m.

What is the charge on each if the force is attractive?

A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 10.0 m/s. the cliff is 50.0 m above a flat horizontal beach. (a) how long after being released does the stone strike the beach before the cliff? (b) find the speed just before the stone strikes the beach. (c) find the traveling horizontal distance for the stone

A 300 kg piano is being lowered into position by a crane while two people steady it with ropes pulling to the sides. Bob's rope pulls to the left, 11 ∘ below the horizontal, with 330 N of tension. Ellen's rope pulls toward the right, 28 ∘ below the horizontal.

Part A

What tension must Ellen maintain in her rope to keep the piano descending vertically at a constant speed?

Express your answer in newtons.

Part B

What is the tension in the vertical main cable supporting the piano?

Express your answer in newtons.

1) Which takes more work, slowing a car from 100km/h to 70km/h, or 70km/h to 0?

2) A 0.2kg falcon flies at 50m/s toward a 0.01kg shrew moving at 0.2m/s away from the falcon. What is the total kinetic energy of the falcon-shrew system?

5) Three capacitors, all initially without any dielectrics inserted, of C1 = 3 micro-farads, C2 = 7 micro-farads, and C3 = 15 micro-farads, are connected purely in series to a battery and the total stored energy of all three capacitors is 203 micro-joules. Then, the plates of C1 are brought closer by a factor of 2 and a dielectric with a dielectric constant of 1.7 is inserted into C2 while still connected in series to the same battery. (C3 does not change at all.) How much does the total stored energy of all three capacitors increase in micro-joules after the capacitors are changed? Not the factor change... how much does the stored energy go up in value.

what other elements does a star burn as fuel besides hydrogen?

A 2 kg ball is 60m in the air with the PE of 1176. It has a bouncing restitution coefficient of 0.50.

Calculate. What is the maximum speed of the ball before it hits the floor?

After hitting the floor, it bounces back up 15m in the air with a final PE of 294.

Calculate. What is the maximum speed of the ball after it hits the floor?

You have two fluids, water and a fluid that has a density that is 3/10 that of water. If a volume of water that has the same mass as

7.40 m³

of the other fluid fills a cubic aquarium, determine the pressure inside at the bottom of the aquarium. (Use 1000 kg/m³ for the density of water.)

___________ Pa