PLEASE ANSWER ALL QUESTIONS! 6,7,8 & 9 QUESTION FOR 6 AND 7: Air resistance has
ID: 1649526 • Letter: P
Question
PLEASE ANSWER ALL QUESTIONS! 6,7,8 & 9
QUESTION FOR 6 AND 7: Air resistance has a quadratic velocity dependence. Water resistance usually has a linear velocity dependence. Consider a bicycle on a road where air resistance is the dominant resistive force on it. Also consider a canoeist on a lake where water resistance is the most important resistive force. As they move, they are both getting tired at the same rate. At the speeds they are both going, the force the canoeist exerts is 1.5 times as big as the force the cyclist exerts. The rate at which someone gets tired is proportional to the force they exert times the velocity at which they are going. Hint: To answer these questions you will have to consider ratios of things at the beginning to things at the end.
6. If both people increase their speed by 50%, which of them will get tired faster?
A) The bicyclist.
B) The canoeist.
C) They both get tired at the same rate.
D) Not enough information is given to determine an answer.
7. Which person will be exerting the larger force at the 50% higher speed?
A) The bicyclist.
B) The canoeist.
C) They have the same force.
D) Not enough information is given to determine an answer.
Problems 8-9 are related to the following scenario:
QUESTION FOR 8 AND 9: A car is traveling around a banked curve. The angle of the curve is adjusted to be optimum for a velocity of 45 miles/hour.
8 ) If the car goes around the curve at a speed of 30 miles/hour, which of the following forces will have to exist to allow the car to safely negotiate the curve?
a. An additional frictional force up the slope.
b. An additional frictional force down the slope.
c. An increased normal force on the car.
d. The wouldn’t have to be any changes in the forces.
9) If the motion of the car is such as to cause an additional frictional force down the slope of the curve, what would happen to the magnitude of the normal force?
A)The normal force would have to decrease.
B)The normal force would remain the same.
C)The normal force would have to increase.
Explanation / Answer
(6) Since the force exerted by the air quadratic velocity dependence.
Means, the force by air is -
Fa = k*v^2
while the force by water is -
Fw = k1*v
hence, force exerted by air is greater for the same velocity.
Hence option (A) is the correct answer.
(7) As explained above, again (A) is your correct answer.
(8) The frictional force will keep the car fall downward. So, its direction is in upward.
hence, (a) is your correct option.
(9) In this case, normal force will increase.
Hence, (C) is your correct option.
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