I) When a car goes around a circular curve on a horizontal road at constant spee
ID: 1864358 • Letter: I
Question
I) When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path? (4 points) A) the normal force from the road B) the friction force from the road C) gravity D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration. Answer: 2) A 1000-kg car is moving at 30 m/s around a horizontal unbanked curve whose diameter is 0.20 km. What is the magnitude of the friction force required to keep the car from sliding? (6 points) A) 9000 N B) 9800 N C) 300 N D) 900 N E) 3000 N Answer: Two points for correct selection. Four points for showing the correct mathematical formulation and the right answer. 3) A 5.0 m diameter merry -go- around is turning with a 4.0 s period (T). The speed of a child () on the rim is: (8 points) A) 9.3 m/s B) 3.9 m/s C) 3.9 rad/s D)9.3 m/s Two points for correct selection. Six points for showing the correct mathematical formulation and the right answer. nswer Selection B) 4) An object is moving in a circular path with a radius of 4.0 m. If the object moves through an angle of 45 degrees, then the angle is. (6 points) A) 0.25 radians B) 0.53 radians C) 0.79 radians D) 1.02 radians E) 1.44 radians Two points for correct selection. Four points for showing the correcet mathematical formulation w right answer Answer:Explanation / Answer
1) while turning on horizontal surface, acceleration of object is parallel to surface. Only force acting parallel to surface is force force of friction.
hence B is correct.
2) Force on object, while moving in circle = MV2/R ( towards center of circle)
Hence Force of friction = 1000*302/100 (radius = 100m)
= 9000 N
Option A is correct
3) Time period of object moving in circle
T = 2 pi R/V
4 = 2 pi 2.5 /V
V = 5 pi/4 = 3.9 m/s
option B
4) 180 deg = pi radian
45 deg = pi*45/180
= 0.79 radians
Option C