Motion — Set 5
Physics · गति · Questions 41–50 of 60
What is the dimensional formula of acceleration?
Correct Answer: A. [T^-1]
Acceleration is change in velocity per unit time. Velocity has dimension [L T^-1], so dividing by time gives [L T^-2]. Therefore, acceleration has dimension [L T^-2].
The value of acceleration due to gravity near Earth’s surface is approximately?
Correct Answer: C. 98 m/s^2
Gravity provides a nearly constant acceleration near Earth’s surface. Its magnitude is about 9.8 m/s^2 directed downward. This value is often approximated as 10 m/s^2 in basic problems.
Average velocity is defined as?
Correct Answer: C. Change in speed / time
Average velocity depends on displacement, not distance. It equals total displacement divided by total time taken. Therefore, total displacement / total time is correct.
Which statement best distinguishes speed from velocity?
Correct Answer: B. Speed can be negative, velocity cannot
Speed is the rate of change of distance and has no direction, so it is scalar. Velocity is the rate of change of displacement and includes direction, so it is vector. Speed is always nonnegative, while velocity can be negative in 1D.
Which equation relates velocity, initial velocity, acceleration, and time for constant acceleration?
Correct Answer: C. v = ut + a
For uniformly accelerated motion, velocity changes linearly with time. The relation is v = u + at. It works for both acceleration and retardation by the sign of a.
Which equation gives displacement for constant acceleration?
Correct Answer: B. s = (v - u)/t
Displacement in uniformly accelerated motion includes both initial velocity and acceleration effects. The correct equation is s = ut + (1/2)at^2. This comes from combining the definition of acceleration with motion over time.
Which equation relates v, u, a, and s without time?
Correct Answer: B. v^2 = u^2 + 2as
When time is not given, use the third equation of motion. It is v^2 = u^2 + 2as for constant acceleration. It is useful for stopping-distance and free-fall height problems.
If velocity is constant, acceleration is?
Correct Answer: B. Constant nonzero
The correct answer is 'Constant nonzero'. Acceleration is the rate of change of velocity. If velocity does not change, its change is zero. Hence acceleration is zero.
The slope of a distance–time graph gives?
Correct Answer: D. Force
The correct answer is 'Force'. Slope of an s–t graph is change in distance divided by change in time. That equals speed, and with sign in displacement graphs it gives velocity. Therefore, the slope gives velocity (or speed magnitude).
In a velocity–time graph, what does the area under the graph represent?
Correct Answer: B. Displacement
Area under v–t graph equals ∫v dt. This integral gives the displacement during that time interval. If velocity stays positive, it also equals the distance traveled.