1) A projectile has the least speed at what point in its path?

a) At its maximum height.

b) Just before it hits the ground.

c) Just after it's fired.

d) After three seconds of travel.

2) The magnitude of a vector can never equal the length of one of its components.

True

False

3) Can a particle with a constant speed ever be accelerating?

a) Yes, because acceleration and velocity are unrelated.

b) No, because its speed is constant.

c) Yes, because it's speed is changing.

d) Yes, if it's changing direction.

A worker is trying to push a crate across the floor in the rightward direction with a horizontal force of 15N. The crate does not move. The mass of the crate is 10kg. The coefficient of static friction is 0.25, and the coefficient of kinetic friction is 0.15. (1) what is the friction on the crate? Give both magnitude and direction of the friction. (2) He then pulls the right edge of the crate with a force of 50N at an angle \Theta =30degrees above the x-axis. Does the crate move? Justify your answer quantitatively. (3) what is the acceleration of the crate if it moves? (4) what is the work done by the workers force when the crate moves 4 meters? (5) what is the work done by the gravitational force in that 4-meters distance? (6) What us the thermal energy dissipated during the move?

Consider a charged disk of radius R on the x-z plane with its centre at the origin. The disk has a positive charge density σ. (a) Find, from first principles, an expression for the electric field of this disk at point P (0,yP,0) on the axis of the disk. (b) A second identical charged disk is now placed at a distance d parallel to the first, with its center at (0,d,0). Find the net electric field due to both disks at a point half way between the two disks at H (0,d/2,0). (c) A positive charge Q is now placed at H.

Use the results of part (b) to write an expression for the electric force acting on this charge. (d) What happens to charge Q if is displaced from H by a very small amount, y (y<<d/2), on the y-axis. Use Newton’s 2nd Law to discuss the motion of Q.

In class, we showed the equation for electroosmotic mobility and electrophoretic mobility. Using these two equations, derive the equation for v_total and t_m. Recall the equation for v_ep = µ_eE and v_eo = µ_eoE

Q = Make quark model for spin 0 meson.

attempt only if you are sure, i will downvote wrong or guessed answer.

1. A certain spring is compressed 0.2 metres from its natural length by a force of 0.02 newtons. A 0.1 kilogram mass is attached to this spring. There is no damping, and the mass is acted on by an external force of 0.05 cos(0.8 t) newtons, where t is measured in seconds. At t = 0, the mass is released, at rest, from its rest (equilibrium) position.

   1. (a) Set up and solve the initial value problem for the displacement x(t) of the mass from its rest (equilibrium) position, where x is measured in metres. Express x(t) as a sum of sinusoidal (i.e. sine or cosine) functions of t.

   2. (b) Express x(t) from part (a) as a product of sinusoidal functions of t, and identify the two “envelope” functions that x(t) oscillates between.

A ball is attached to one end of a wire, the other end being fastened to the ceiling. The wire is held horizontal, and the ball is released from rest (see the drawing). It swings downward and strikes a block initially at rest on a horizontal frictionless surface. Air resistance is negligible, and the collision is elastic. The masses of the ball and block are, respectively, 1.6 kg and 2.3 kg, and the length of the wire is 1.21 m. Find the velocity (magnitude and direction) of the ball (a) just before the collision, and (b) just after the collision.

In the figure particle 1 of charge +q and particle 2 of charge +4q are held at separation L = 8.38 cm on an x axis. If particle 3 of charge q₃ is to be located such that the three particles remain in place when released, what must be the (a) x and (b) y coordinates of particle 3 and (c) the ratio q₃/q?

a) Interaction between particles is described by exchange of virtual bosons. The range of interaction is inversely proportional to the rest mass of these exchange bosons. Explain using diagrams why the force responsible for binding nucleons into nucleus has a range of ~10-15 m, even though the rest mass of the exchange gluons is zero.

b) Using appropriate Feynman diagrams for the electromagnetic interaction between two electrons, as well as for the strong interaction between quarks and gluons, contrast the electromagnetic and strong interaction at large distances. Using these arguments, explain why quarks are confined into hadrons.

1. Formulate the Second Law of thermodynamics and explain why the simple example of a kitchen refrigerator does not violate it.

• A 600 kg elevator accelerates upward from rest for 10 seconds through 40.0 m. Find the cable tension.
• a) 5130 N
• b) 5400 N
• c) 6360 N
• d) 6630 N

The absolute zero temperature is equal to 0 k or -273.15. Why we cannot create objects with even lower temperature than 0k? Why the absolute zero temperature exists? What happens ( on microscopic scale) to atoms and molecules when their temperature is near the absolute zero?

There are three ways that radiating light can interact with matter. (a)List those 
processes and Illustrate each processes using simple two level system. (b) which 
one is the basis of lasing? (c) In that (lasing) process, explain why emitted photon 
has the same phase, polarization and direction as the exciting photon.

A person pushes a 500kg crate with a force of 700 N across a concrete floor. Given the coefficicent of kinetic friction is 0.100 what is the acceleration of the crate across the floor?

A cue ball traveling at 4.0 m/s makes a glancing, elastic collision with a target ball of equal mass that is initially at rest. The cue ball is deflected so that it makes an angle of 30° with its original direction of travel.

(a) Find the angle between the velocity vectors of the two balls after the collision. °

(b) Find the speed of each ball after the collision. cue ball m/s target ball m/s