Form A

Sample Exam 2

1/ A roller coaster car is moving toward a slope, as shown. The speed is v₀ = 10 m/s. The height of the slope is H = 3 m. Assuming friction is negligible, calculate the speed of the car at the top of the slope.

(A) 12.6 m/s (B) 9.5 m/s

2/ Is an energy crisis possible? Choose the best answer.

(A) No, because energy is always conserved.

(B) Yes, because an energy source can run into a shortage.

(D) Yes, because energy always declines as it gets used up.

(E) No, because the free market will always ensure adequate energy supplies.

3/ The archer pulls the arrow back, exerting a force F = 111 N to produce a displacement of x = 0.2 m. The bow may be considered to be a Hooke spring, with spring constant k = F/x = 555 N/m. Determine the speed of the arrow when she releases it, if the mass of the arrow is 0.05 kg.

(A) 21.1 m/s (B) 47.1 m/s

4/ See the figure. A man pulls the rope with a force F = 98 N. The rope goes over a pulley and lifts a bucket with mass m = 10 kg. The bucket rises 5 meters in 6 seconds. Calculate the power supplied by the man?

(A) 73 joules (B) 73 watts

5/ I assume that you know whether a block of wood (white pine, say) will float or sink in water. Now, compare the volume of 1 kg of wood to the volume of 1 kg of water.

(A) The volume of the water is larger.

(B) The volume of the wood is larger.

(D) More information is needed to compare the volumes.

6/ At what depth is the pressure of water in a lake equal to 4 atm? (1 atm = 1.013 x 10⁵ N/m² )

(A) 31.0 m (B) 27.0 m

7/ A canoe that is made of concrete …

(A) … cannot float in water because concrete is more dense than water.

(B) … can only float if the interior air space is enclosed by a water-tight cover.

(D) … cannot float because it is heavier than water.

8/ The volume of the inner tube is 0.13 m³. What is the maximum mass that it can hold up floating in water?

(A) 13 kg (B) 65 kg

9/ Two charged spheres (L and S) have equal charges, Q = 1.0x10^-6 C on each sphere. The center of the smaller sphere (S) is located at a distance of 10 cm from the center of the larger sphere (L). Calculate the force on L.

(A) 8.99´10⁵ N (B) 0.0899 N

10/ In the figure, ABC forms an equilateral triangle. Two equal positive charges are located at the positions A and B. What is the direction of the electric field at point C?

(A) North (B) South

11/ A 1 farad capacitor is charged by a 5 volt battery.

What are the charges on the plates?

(A) +0.2 C and -0.2 C (B) +0.2 C on both plates

12/ Consider the figure. The strength of the electric field at P is 3´10⁴ N/C. What is the electric charge (Q) of the sphere?

(A) 3.3 x 10^-4 C (B) 1.8 x 10^-4 C

13/ Consider these three statements, “a”, “b”, “c”:

“a” - Like charges repel when there is no electric field.

“b” - If a charge is placed in an electric field, the electric field exerts a force on the charge.

“c” - The direction of the field due to a negative charge points away from the charge.

Which statements are true?

(A) “a” only (B) “b” only (C) “a” and “b”

(D) “a” and “c” (E) “a”, “b”, and “c”

14/ A 6 volt battery is connected to a light bulb, which then uses 15 watts of power. What is the current?

(A) 3.00 A (B) 2.50 A

15/ What causes the resistance of a wire?

(A) The electrons move slowly.

(B) Electrons and ions move in opposite directions because they have opposite signs of the charge.

(D) The electrons collide with the ions.

16/ A current of 6.0 amps flows in a wire with electrical resistance of 1.1 ohms. If the current flows for 5 minutes, how many electrons have passed a cross section of the wire?

(A) 1.12 x 10²² (B) 1.88 x 10²⁰

(D) not enough information is given because the answer would depend on the speed of the electrons.