Biology Forums - Study Force

A 0.20-km wide river has a uniform flow speed of 3.0 m/s toward the east. A boat with a speed of 8.0 m/s relative to the water leaves the south bank and heads in such a way that it crosses to a point directly north of its departure point. How long does it take the boat to cross the river?
 a. 29 s
  b. 23 s
  c. 25 s
  d. 27 s
  e. 17 s

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[Ques. 2]

In this figure a light ray travels between air and glass. Which way did the light ray go?
   

 
   
  a.
  from the air into the glass
   
  b.
  from the glass into the air
   
  c.
  either A or B.
   
  d.
  None of the abovethis depicts an impossible situation.

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[Ques. 3] A 0.20-km wide river has a uniform flow speed of 4.0 m/s toward the east. It takes 20 s for a boat to cross the river to a point directly north of its departure point on the south bank. In what direction must the boat be pointed in order to accomplish this?
 a. 23 west of north
  b. 20 west of north
  c. 24 west of north
  d. 22 west of north
  e. 17 west of north

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[Ques. 4] A 0.14-km wide river flows with a uniform speed of 4.0 m/s toward the east. It takes 20 s for a boat to cross the river to a point directly north of its departure point on the south bank. What is the speed of the boat relative to the water?
 a. 5.7 m/s
  b. 8.5 m/s
  c. 8.1 m/s
  d. 7.0 m/s
  e. 6.4 m/s

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[Ques. 5]

Which angle is the angle of incidence for the light ray shown approaching the plane mirror?
   

 
   
  a.
  60
   
  b.
  30
   
  c.
  neither
   
  d.
  either

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[Ques. 6] A car travels in a flat circle of radius R. At a certain instant the velocity of the car is 24 m/s west, and the acceleration of the car has components of 2.4 m/s2 east and 1.8 m/s2 south. What is the radius of the circle?
 a. 0.24 km
  b. 0.19 km
  c. 0.32 km
  d. 0.14 km
  e. 0.27 km

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[Ques. 7] The speed of a particle moving in a circle 2.0 m in radius increases at the constant rate of 4.4 m/s2 . At an instant when the magnitude of the total acceleration is 6.0 m/s2, what is the speed of the particle?
 a. 3.9 m/s
  b. 2.9 m/s
  c. 3.5 m/s
  d. 3.0 m/s
  e. 1.4 m/s

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[Ques. 8]

Which of the lines in the figure represents the normal to the surface at point P?
   

 
   
  a.
  1
   
  b.
  2
   
  c.
  3
   
  d.
  4
   
  e.
  none of the above

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[Ques. 9] A car travels in a flat circle of radius R. At a certain instant the velocity of the car is 24 m/s west, and the total acceleration of the car is 2.5 m/s2 53 north of west. Which of the following is correct?
 a. R = 0.29 km, and the car's speed is increasing.
  b. R = 0.23 km, and the car's speed is decreasing.
  c. R = 0.23 km, and the car's speed is increasing.
  d. R = 0.29 km, and the car's speed is decreasing.
  e. R = 0.29 km, and the car's speed is constant.

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[Ques. 10]

The electric field shown is produced by a single point charge at the center of the picture.
   

 
  What force might a charge placed at location D feel?
   
  a.
  zero
   
  b.
  an upward force
   
  c.
  a downward force
   
  d.
  a force to the right
   
  e.
  a force to the left

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