Past JEE Questions
Give the correct answer/choice
1. A thin circular ring of mass ‘M’ and radius ‘r’ is rotating about its axis with a constant angular velocity ω. Two objects, each of mass m, are attached gently to the opposite ends of a diameter of the ring. The wheel now rotates with an angular velocity
a. ω M/(M+m)
c. ω M/(M+2m)
d. ω (M+2m)/M
2. A satellite is launched into a circular orbit of radius R around the earth. A second satellite is launched into an orbit of radius 1.01R. The period of the second satellite is larger than the first one by approximately.
3. Two point masses of 0.3 kg and 0.7 kg are fixed at the ends of a rod of length 1.4 m and of negligible mass. The rod is set rotating about an axis perpendicular to its length with a uniform angular speed. The point on the rod through which the axis should pass in order that the work required for rotation of the rod is minimum, is located at a distance of
a. 0.42 m from mass of 0.3 kg
b. 0.70 m from mass of 0.7 kg
c. 0.98 m from mass of 0.3 kg
d. 0.98 m from mass of 0.7 kg
4. If the distance between the earth and the sun were half its present value, the number of days in a year would have been
1. A circular road of radius r is banked for a speed of v = 40 km/hr. A car of mass m attempts to go on the circular road. The friction coefficient between the tyre and the road is negligible.
a. The car cannot make a turn without skidding.
b. If the car turns at a speed less than 40 km/hr, it will slip down.
c. If the car turns at the correct speed of 40 km/hr, the force by the road on the car is equal to mv²/r.
d. If the car turns at the correct speed of 40 km/hr, the force by the road on the car is greater than mg as well as greater than mv²/r.