Motion — Set 6
Physics · गति · Questions 51–60 of 60
Centripetal acceleration for uniform circular motion is?
Correct Answer: A. a = r/v^2
In circular motion, acceleration is directed toward the center and depends on speed and radius. The correct formula is a = v^2/r. Higher speed or smaller radius increases centripetal acceleration.
The relation between linear speed v and angular speed ω in circular motion is?
Correct Answer: D. v = r^2ω
In one revolution, arc length traveled is 2πr and angular displacement is 2π rad. So linear speed is proportional to radius times angular speed. Therefore, v = rω is correct.
The SI unit of angular displacement is?
Correct Answer: D. Degree
Angular displacement measures how much angle is swept. The SI unit for angle is radian. Degrees and revolutions are common but not SI units.
Frequency (f) and time period (T) are related by?
Correct Answer: C. f = T^2
Time period is the time for one cycle. Frequency is the number of cycles per second. So f = 1/T.
Time of flight of a projectile launched with speed u at angle θ (level ground, no air resistance) is?
Correct Answer: A. (u cosθ)/g
Vertical motion determines the time of flight. Initial vertical velocity is u sinθ, and it returns to the same level under gravity. Thus time of flight T = 2u sinθ / g.
Range of a projectile on level ground is?
Correct Answer: B. (u^2 sin2θ)/g
Range depends on horizontal speed and time of flight. For level ground without air resistance, the standard result is R = (u^2 sin2θ)/g. Maximum range occurs when sin2θ is maximum.
For a projectile launched with fixed speed u on level ground, maximum range occurs at angle?
Correct Answer: A. 60°
Range R = (u^2 sin2θ)/g for level ground. This is maximum when sin2θ = 1, meaning 2θ = 90°. Therefore, θ = 45° gives maximum range.
Relative velocity of A with respect to B is generally given by?
Correct Answer: D. vA - vB
Relative velocity is found by subtracting the velocity vectors. Velocity of A with respect to B is vA - vB. This works for both same and opposite directions using vector signs.
For constant acceleration, the average velocity over a time interval is?
Correct Answer: D. uv
With constant acceleration, velocity changes uniformly from u to v. The average value of a uniformly changing quantity is the mean of initial and final values. Hence average velocity = (u + v)/2.
The area under a velocity-time graph represents?
Correct Answer: A. Displacement
The area under a velocity-time graph gives the displacement of the object. If the graph is above the time axis, displacement is positive; if below, it is negative. This is a fundamental concept in kinematics.