2. The diagram below represents a uniform ladder leaning safely against a real wall. Which of the following diagrams most correctly represents all the forces acting on the ladder?
(A)
(B)
(C)
(D)
(E)

1. Imagine that a cell had no motor proteins. Which processes would not be able to occur? (A) RNA transcription (B)fertilization of an egg by a sperm cell (C)protein translation (D)maintenance of cell rigidity (E)action potential of a neuron

2. For a neuron with an initial membrane potential at -80 mV, an increase in the extracellular concentration of potassium ions from 5 mM to 35 mM would result in _____.(A) depolarization of the neuron (B)hyperpolarization of the neuron (C)net diffusion of potassium ions into the cell (D)no change in the membrane potential

3. If the afferent nerves from the carotid and aortic bodies are cut in a rat, (A) a decrease in arterial PCO2 will stimulate increased ventilation. (B)an increase of PCO2 in the cerebrospinal fluid will no longer stimulate increased ventilation. (C)an increase in arterial lactic acid (metabolic acid) will no longer stimulate increased ventilation. (D)an increase in arterial PCO2 will no longer stimulate increased ventilation. (E)a decrease in arterial PO2 will stimulate increased ventilation.

1. A boy wants to row across a river in the shortest possible time. He can row at 2 m/s in still water and the river is flowing at 1 m/s. At what angle θ should he point the bow (front) of his boat? (A) 30° (B) 45° (C) 60° (D) 53° (E) 90°.

3. At time t = 0 a particle starts moving along the x axis. If its kinetic energy increases uniformly with t, the net force acting on it must be: (A) constant (B) proportional to (C) proportional to 1/ (D) proportional to t (E) proportional to 1/t.

4. A 0.20-kg particle moves along the x axis under the influence of a conservative force field. The potential energy is given byU(x) = (8.0J/m²)x² + (2.0J/m²)x⁴, where x is in coordinate of the particle. If the particle has a speed of 5.0 m/s when it is at the origin, what is its speed when it is at x =1.0 m? (A) 0 (B) 2.5 m/s (C) 7.9 m/s (D) 11 m/s (E) The particle can't reach the position x = 1.0 m.

5. A 3.0-kg and a 2.0-kg cart approach each other on a horizontal air track. They collide and stick together. After the collision, their total kinetic energy is 40 J. The speed of their center of mass is: (A) 2.8 m/s(B) 4.0 m/s(C) 5.2 m/s(D) 6.3 m/s(E) 0 m/s.

6. A 16 kg block is attached to a cord that is wrapped around the rim of a flywheel of diameter 0.40 m and hangs vertically. The rotational inertia of the flywheel I is 0.50 kg.m². When the block is released and the cord unwinds, the acceleration of the block is:(A) 0.15g (B) 0.56g (C) 0.84g (D) g (E) 1.3g.

7. A rigid and uniform rod of length L and mass M is free to rotate about the axis through its center and perpendicular to the rod (rotational inertia I=(1/12)ML²). A small particle also of mass M is moving perpendicular to the rod at a speed v, and it strikes the rod a distance (1/4)L from the center. If the particle sticks firmly to the rod, find the angular velocity (ω) of the system about the fixed axis after the collision. (A) 1.71 v/L (B) 2.16 v/L (C) 4.00 v/L (D) 4.22 v/L (E) 4.60 v/L.

8. The displacement of an object oscillating on a spring is given by x(t) = xmcos(wt +Φ). If the object is initially displaced in the negative x direction and given a negative initial velocity, then the phase constant Φ is between: (A) 3π/2 and 2π radians (B) π and 3π/2 radians (C) π/2 and π radians (D) 0 and π/2 radians (E) none of the above (Φ= π).