Mixed Questions — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Mixed Questions MCQs with step-by-step solutions (36 questions). Part of Motion in 1 Dimension. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Mixed Questions · medium · theory
A car starts from rest with acceleration $2$ m/s² for $10$ s. The distance covered is
A. $20$ m
B. $100$ m ✓ Correct
C. $40$ m
D. $200$ m
Solution: $s = \frac{1}{2}\times2\times100 = 100$ m (and $v$ reaches 20 m/s).
Q2 — Mixed Questions · medium · theory
A body moving at $20$ m/s is brought to rest by a uniform retardation of $4$ m/s². The stopping distance is
A. $100$ m
B. $50$ m ✓ Correct
C. $25$ m
D. $80$ m
Solution: $v^2 = u^2 - 2as$: $0 = 400 - 8s \Rightarrow s = 50$ m.
Q3 — Mixed Questions · medium · numerical
Under uniform acceleration a body’s velocity grows from $10$ m/s to $30$ m/s. Its average velocity over the interval is
A. $20$ m/s ✓ Correct
B. $15$ m/s
C. $25$ m/s
D. $40$ m/s
Solution: Linear change: $\bar v = \frac{u+v}{2} = 20$ m/s.
Q4 — Mixed Questions · easy · theory
A car travels at $20$ km/h for the first half of the total TIME and $30$ km/h for the second half. Its average speed is
A. $25$ km/h ✓ Correct
B. $24$ km/h
C. $50$ km/h
D. $26$ km/h
Solution: Equal times → arithmetic mean: $\frac{20+30}{2} = 25$ km/h.
Q5 — Mixed Questions · medium · theory
A thief drives at $25$ m/s, $100$ m ahead of a police car doing $30$ m/s. The police catch up in
A. $10$ s
B. $4$ s
C. $25$ s
D. $20$ s ✓ Correct
Solution: Relative speed $= 5$ m/s closing a $100$ m gap: $t = \frac{100}{5} = 20$ s.
Q6 — Mixed Questions · medium · theory
Two trains, $900$ m apart, approach each other at $54$ km/h and $36$ km/h. They meet after
A. $60$ s
B. $36$ s ✓ Correct
C. $18$ s
D. $90$ s
Solution: Relative speed $= 15 + 10 = 25$ m/s; $t = \frac{900}{25} = 36$ s.
Q7 — Mixed Questions · easy · numerical
A car at $72$ km/h stops in $20$ m under uniform braking. The magnitude of the retardation is
A. $20$ m/s²
B. $2$ m/s²
C. $10$ m/s² ✓ Correct
D. $5$ m/s²
Solution: $u = 20$ m/s; $0 = 400 - 2a(20) \Rightarrow a = 10$ m/s².
Q8 — Mixed Questions · medium · theory
A driver’s reaction time is $0.5$ s. At $20$ m/s, the distance covered BEFORE the brakes are even applied is
A. $10$ m ✓ Correct
B. $5$ m
C. $20$ m
D. $40$ m
Solution: Reaction distance $= 20\times0.5 = 10$ m at unchanged speed.
Q9 — Mixed Questions · medium · theory
A stone falls freely from rest for $3$ s (total). The distance covered in the LAST TWO seconds is ($g = 10$ m/s²)
A. $40$ m ✓ Correct
B. $45$ m
C. $25$ m
D. $20$ m
Solution: Total $= 45$ m; first second $= 5$ m; last two seconds $= 40$ m.
Q10 — Mixed Questions · easy · theory
The position of a particle is $x = 40 + 12t - t^3$ (metres, seconds). It comes to rest at $t =$
A. $1$ s
B. $6$ s
C. $2$ s ✓ Correct
D. $4$ s
Solution: $v = 12 - 3t^2 = 0 \Rightarrow t^2 = 4 \Rightarrow t = 2$ s. (A classic exam problem.)
Q11 — Mixed Questions · medium · numerical
A body starts from rest with uniform acceleration and covers $7$ m in the $4$th second. Its acceleration is
A. $3.5$ m/s²
B. $7$ m/s²
C. $2$ m/s² ✓ Correct
D. $1$ m/s²
Solution: $s_n = \frac{a}{2}(2n-1)$: $7 = \frac{a}{2}\times7 \Rightarrow a = 2$ m/s².
Q12 — Mixed Questions · medium · theory
A stone is released from a balloon RISING at $5$ m/s. Just after release, the stone
A. Falls immediately
B. Moves up momentarily, then falls ✓ Correct
C. Moves up forever
D. Stays still
Solution: It inherits the balloon’s upward velocity, decelerates under gravity, then falls — a favourite trap.
Q13 — Mixed Questions · medium · theory
A coin is dropped inside a lift that is accelerating UPWARD. Relative to the lift floor, the coin falls
A. Faster than in a stationary lift ✓ Correct
B. It doesn’t fall
C. At the same rate
D. Slower
Solution: In the lift frame the effective gravity is $g + a$, so the coin reaches the floor sooner.
Q14 — Mixed Questions · medium · theory
If the displacement of a body is proportional to $t^2$, the body moves with
A. Decreasing acceleration
B. Increasing acceleration
C. Uniform velocity
D. Uniform acceleration ✓ Correct
Solution: $s \propto t^2$ matches $s = \frac{1}{2}at^2$ — constant acceleration.
Q15 — Mixed Questions · easy · theory
For uniformly accelerated motion starting from rest, a graph of $v^2$ against $s$ is
A. A parabola
B. A straight line with slope $2a$ ✓ Correct
C. A circle
D. A horizontal line
Solution: $v^2 = 2as$ — linear in $s$ with slope $2a$.
Q16 — Mixed Questions · medium · numerical
A body starting from rest covers $100$ m in $5$ s under uniform acceleration. The acceleration is
A. $20$ m/s²
B. $4$ m/s²
C. $10$ m/s²
D. $8$ m/s² ✓ Correct
Solution: $100 = \frac{1}{2}a\times25 \Rightarrow a = 8$ m/s².
Q17 — Mixed Questions · medium · numerical
The times taken to fall freely (from rest) through heights $h$ and $4h$ are in the ratio
A. $2:1$
B. $1:4$
C. $1:2$ ✓ Correct
D. $1:\sqrt{2}$
Solution: $t = \sqrt{\frac{2h}{g}} \propto \sqrt{h}$: $\sqrt{h}:\sqrt{4h} = 1:2$.
Q18 — Mixed Questions · easy · numerical
A bullet moving at $100$ m/s penetrates $10$ cm into a wooden block and stops. The magnitude of its (assumed uniform) retardation is
A. $10^3$ m/s²
B. $5\times10^2$ m/s²
C. $5\times10^4$ m/s² ✓ Correct
D. $10^5$ m/s²
Solution: $0 = (100)^2 - 2a(0.1) \Rightarrow a = \frac{10^4}{0.2} = 5\times10^4$ m/s².
Q19 — Mixed Questions · medium · theory
Car A passes a stationary car B at a constant $20$ m/s. At that instant B starts with acceleration $4$ m/s². B catches A after
A. $8$ s
B. $5$ s
C. $10$ s ✓ Correct
D. $20$ s
Solution: Equal distances: $20t = \frac{1}{2}\times4t^2 \Rightarrow t = 10$ s.
Q20 — Mixed Questions · easy · theory
A stone is dropped into a well and hits the water after $2$ s (ignore the sound’s travel time, $g = 10$ m/s²). The depth of the well is
A. $20$ m ✓ Correct
B. $10$ m
C. $40$ m
D. $5$ m
Solution: $h = \frac{1}{2}\times10\times4 = 20$ m.
Q21 — Mixed Questions · medium · theory
A journey has three equal-distance parts covered at $20$, $30$ and $60$ km/h. The average speed for the whole journey is
A. $40$ km/h
B. $30$ km/h ✓ Correct
C. $36.7$ km/h
D. $25$ km/h
Solution: Times: $\frac{d}{20}+\frac{d}{30}+\frac{d}{60} = \frac{6d}{60} = \frac{d}{10}$. Average $= \frac{3d}{d/10} = 30$ km/h.
Q22 — Mixed Questions · medium · theory
A car moving at $54$ km/h stops uniformly in $3$ s. The distance covered while stopping is
A. $15$ m
B. $27$ m
C. $22.5$ m ✓ Correct
D. $45$ m
Solution: $u = 15$ m/s; $s = \bar v\,t = \frac{15+0}{2}\times3 = 22.5$ m.
Q23 — Mixed Questions · medium · theory
Two stones are dropped from the same point $1$ s apart. When the second stone has fallen for $1$ s, the separation between them is ($g = 10$ m/s²)
A. $15$ m ✓ Correct
B. $10$ m
C. $20$ m
D. $5$ m
Solution: First stone: $2$ s $\to 20$ m; second: $1$ s $\to 5$ m. Gap $= 15$ m.
Q24 — Mixed Questions · easy · theory
A body covers equal displacements in equal intervals of time, however small. Its motion is
A. Random
B. Uniform velocity ✓ Correct
C. Uniformly accelerated
D. Oscillatory
Solution: That is the very definition of uniform (constant) velocity.
Q25 — Mixed Questions · medium · numerical
A uniformly accelerating body covers $20$ m in the $4$th second and $24$ m in the $5$th second. Its acceleration is
A. $4$ m/s² ✓ Correct
B. $2$ m/s²
C. $44$ m/s²
D. $6$ m/s²
Solution: Successive-second distances differ by exactly $a$: $24 - 20 = 4$ m/s².
Q26 — Mixed Questions · medium · theory
A ball dropped from $20$ m rebounds with HALF the speed it hit the ground with. The height it rebounds to is ($g = 10$ m/s²)
A. $15$ m
B. $2.5$ m
C. $5$ m ✓ Correct
D. $10$ m
Solution: Impact speed $= 20$ m/s; rebound at $10$ m/s: $h = \frac{10^2}{2\times10} = 5$ m (a quarter of the drop — $h \propto v^2$).
Q27 — Mixed Questions · medium · numerical
Two cars move side by side at the same velocity of $20$ m/s. The velocity of one relative to the other is
A. Zero ✓ Correct
B. $40$ m/s
C. $10$ m/s
D. $20$ m/s
Solution: Identical velocities: $\vec v_{rel} = \vec v_1 - \vec v_2 = 0$ — they appear stationary to each other.
Q28 — Mixed Questions · medium · theory
The position of a particle is $x = at + bt^2$. Its acceleration is
A. $2b$ ✓ Correct
B. $b$
C. $2a$
D. $a + 2b$
Solution: $v = a + 2bt$, so acceleration $= \frac{dv}{dt} = 2b$ (constant).
Q29 — Mixed Questions · medium · theory
A ball thrown vertically up takes time $T$ to reach the top. The maximum height is ($g$ = acceleration due to gravity)
A. $2gT^2$
B. $\frac{1}{2}gT^2$ ✓ Correct
C. $\frac{gT}{2}$
D. $gT^2$
Solution: By symmetry it falls from the top in time $T$: $H = \frac{1}{2}gT^2$.
Q30 — Mixed Questions · medium · theory
For a ball thrown vertically upward, which quantity remains CONSTANT during the flight (ignoring air)?
A. Acceleration ✓ Correct
B. Kinetic energy
C. Velocity
D. Speed
Solution: Only the acceleration ($g$, downward) never changes; velocity, speed and KE all vary.