Test Prep Test Prep Certifications OAT Questions & Answers

• Question 231:

  A cannon is fired at an angle of 30° above the ground, with an initial velocity of 100 m/s. How long will it take for the cannon ball to hit the ground assuming there is no air resistance?

  A. 10 seconds

  B. 20 seconds

  C. 50 seconds

  D. 100 seconds

  E. Cannot be calculated with this information.

  Correct Answer: A

  Visualize the problem as a vector, and find the y component of it: 100 m/s × sin30 = 50 m/s.

  This means the cannon traveled 50 meters up, and 50 meters down in the y direction. Gravity is 10 m/s2,

  thus it took 5 seconds to go up, and another 5 seconds to go down, totaling an air time of 10 seconds.

• Question 232:

  A circuit contains a 2 and a 5 resistor, connected in parallel to each other. What is the equivalent resistance in this circuit?

  A. 7

  B. 10

  C. 0.7

  D. 10/7

  E. 5/2

  Correct Answer: D

  Resistors in parallel add via: 1/Req = 1/R + 1/R... 1/Req = 1/2 + 1/5 Finding a common denominator: 5/10 + 2/10 = 7/10 = 1/Req Flipping it to attain Req = 10/7

• Question 233:

  A man lifts a 200 lb rock from the floor to a height 6 feet of the ground. How much work must the man perform in order to keep the object in the air?

  A. 1200 ft lb

  B. 33.3 ft lb

  C. 0 ft lb

  D. 2000 ft lb

  E. Not enough information is provided

  Correct Answer: C

  Work = Force ?Distance. Because the question asks about the work performed to keep the rock above the man, the rock is not being displaced, and thus, no work is being done as displacement = 0. Work is only being done in reference to the actual displacement movement. Be careful for questions that give you meaningless information in relation to the answer.

• Question 234:

  A bat uses echolocation to identify objects. A bat is traveling to west emits a sound (also heading towards the west) to a stationary object. Which of the following is most accurate in regards to the Doppler effect?

  A. Frequency will be the same.

  B. Frequency will be higher than the originally emitted one.

  C. Frequency will be lower than the originally emitted one.

  D. Frequency will not return.

  E. Cannot determine.

  Correct Answer: B

  This is characteristic of the Doppler effect. If 2 objects are approaching another, or if one is stationary and the other is approaching the object, then the received frequency will be higher than the emitted frequency.

• Question 235:

  A thermostat with an initial reading of 100癋 rises up by 50癋 in 20 minutes. What is the final temperature reading of the thermostat in Celsius?

  A. 150° C

  B. 423° C

  C. 65.6° C

  D. 70° C

  E. 60° C

  Correct Answer: C

  This is a simple conversion problem that may appear in either (or both) the physics and QR section. It is important you understand how to convert between Celsius, Fahrenheit and Kelvin.

  °K = 273.15 + °C °C = 5/9 × °F − 32 °F = 9/5 × °C + 32

  Using the 2nd equation above, plugging in 150 for F produces ~65.5 °C

• Question 236:

  For the incline plane diagram below, which of the answer choices best represents the normal force experienced by this block?

  

  A. mg

  B. mgsin

  C. mgcos

  D. µmgcosθ

  E. ma

  Correct Answer: C

  In an inclined plane, the normal force is mgcos. It is important you know all aspects of a incline plane problem as it is an almost guaranteed question. If one did not know the equation for the normal force, one could not calculate it if presented with numbers.

• Question 237:

  For the following vector, if was 60? what will be the measure of the 'x' component of this vector?

  

  A. 0.87

  B. 0.5

  C. 50

  D. 8.7

  E. None of the above

  Correct Answer: E

  Without the magnitude of the vector itself, one cannot calculate the x or y components of the vector. You would need the angle (provided) and the magnitude (not provided) to calculate either components.

• Question 238:

  A yoyo is being swung around with an angular velocity of 30 and a radius of 3. What is the yoyo's linear velocity?

  A. 90

  B. 45

  C. 33

  D. 30

  E. Not enough information given.

  Correct Answer: A

  The relationship between angular velocity to linear velocity is:

  v = wr

  v = linear velocity; w = angular velocity; r = radius

  Ignoring units for this problem to make it easier, we find v = 30 × 3 = 90.

• Question 239:

  What is the hydrostatic pressure in a pond at a depth of 100 m? (Density of water = 1000 kg/m3)

  A. 1.0 × 106 Pa

  B. 1.0 × 106 atm

  C. 1.0 × 105 Pa

  D. 1.0 × 105 atm

  E. 300 Pa

  Correct Answer: A

  Hydrostatic Pressure = gD where:

  = Density of fluid (1000 kg/m?here, as given) g = Gravity (unless stated otherwise, this is 10 m/s? D = Depth (100 m, as given)

  Simply plug and chug. Remember the SI unit of pressure is Pascal (Pa). Since all given units are in their respective SI formats, no conversion is needed.

• Question 240:

  A joule is equal to:

  A. (kg × m) / s

  B. kg2/s3

  C. (kg × m2) / s2

  D. m/s3

  E. N × m4

  Correct Answer: C

  A joule is indeed equal to this. Joule, the unit of work, can be identified as equal to force x distance.

  Force (in newtons), is equal to mass × acceleration.

  Mass = kg Acceleration = m/s2 Distance = m

  Thus, combining all these terms by multiplying them: kg × (m/s2) × m = (kg × m2) / s2