1.) A Ford Focus with a surface area of 3.00 m^2 is driving on a highway at a sp
ID: 1884332 • Letter: 1
Question
1.) A Ford Focus with a surface area of 3.00 m^2 is driving on a highway at a speed of 88.0 km/hr, then accelerates to 113 km/hr to pass another car. How much more force does the motor have to supply to overcome air resistance at the higher speed? Assume the density of air the car is traveling through is 1.21 kg/m^3.
A. The engine must supply 28.5 N more force at 113 km/hr. B. The engine must supply 227 N more force at 113 km/hr. C. The engine must supply 454 N more force at 113 km/hr. D. The engine must supply 1459 N more force at 113 km/hr.
2.) Is an object in uniform circular motion accelerating? Why or why not?
A. Yes, because the velocity is not constant. B. No, because the velocity is not constant. C. Yes, because the velocity is constant. D. No, because the velocity is constant.
3.) Imagine you apply a slowly increasing force to a box sitting on a table. You plot the magnitude of the applied force on the x axis and the magnitude of the friction force on the y axis. Describe the main attributes of the plot.
A. The force of friction would be constant, independent of the applied force. B. The magnitude of the force of friction will increase at the same rate as the applied force. C. The magnitude of the friction force will increase with unity slope until the maximum force of static friction is reached. The friction force will then drop down slightly to the magnitude of the kinetic friction force and will remain constant at this level as the applied force continues to increase. D. The magnitude of the friction force will increase with unity slope until the maximum force of static friction is reached. The friction force will then increase slightly to the magnitude of the kinetic friction force and will remain constant at this level as the applied force continues to increase.
4.) How much work is done when a weightlifter lifts a 200N barbell from the floor to a height of 2m?
A. 0 J B. 100 J C. 200 J D. 400 J
5.) A man with a mass of 60kg climbs two flights of stairs to the third floor of a building. If he gains 6m in altitude and g is 10m/s^2, what is his potential energy gain?
A. 60 J B. 360 J C. 600 J D. 3600 J
Explanation / Answer
3)The magnitude of the friction force will increase with unity slope until the maximum force of static friction is reached. The friction force will then increase slightly to the magnitude of the kinetic friction force and will remain constant at this level as the applied force continues to increase.
Since its is on the table and moving wish the help of pushing force, intially
Ffs = us N
later when it starts moving
Ffk = uk N
Ffs < Ffk ; for the pbject to move
4)400 J
W = = m g h = F d = 200 x 2 = 400 m
5)3600 J
PE = m g h = 60 x10 x 6 = 3600 J
[for first, F = C rho v^2 A/2 ; value of C is required]
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