Is Motion in a Straight Line part of the EAPCET Physics syllabus?

Yes. Motion in a Straight Line is taught in Intermediate first year Physics, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.

How many Physics questions are there in EAPCET?

40 of the 160 questions in the Engineering paper are Physics, spread across 30 chapters.

What mistakes do students make in Motion in a Straight Line?

Using speeds in km/h inside the equations of motion — multiply by 5/18 to convert to m/s first. Treating distance and displacement as equal when the body reverses direction — split the motion at the point where v = 0. Taking g as positive for an upward-thrown body while also taking upward as positive — with upward positive, a = −g. Applying the constant-acceleration equations when acceleration varies with time — integrate a(t) or use the graph instead.

EAPCET Physics · Intermediate first year

Motion in a Straight Line

Motion in a Straight Line describes motion in one dimension: displacement, velocity and acceleration, the equations of uniformly accelerated motion, graphs and relative velocity.

Subject: Physics
Taught in: Intermediate first year
Physics in the paper: 40 of 160 questions

Key formulas and results

$v = u + at$ , $s = ut + \tfrac{1}{2}at^{2}$ , $v^{2} = u^{2} + 2as$
Distance covered in the nth second: $s_{n} = u + \frac{a}{2}(2n - 1)$
Displacement = area under the velocity–time graph
Acceleration = slope of the velocity–time graph
Relative velocity of A with respect to B: $v_{AB} = v_{A} - v_{B}$
Velocity = slope of the position–time graph
Change in velocity = area under the acceleration–time graph
Acceleration in terms of position: $a = v\frac{dv}{dx}$
Area under the acceleration–position graph $= \frac{v^{2} - u^{2}}{2}$
Distance fallen in the last second of a free fall lasting $T$ seconds: $\tfrac{1}{2}gT^{2} - \tfrac{1}{2}g(T - 1)^{2} = g\left(T - \tfrac{1}{2}\right)$
Bullet and planks: if a bullet loses $1/n$ of its speed in one plank, it stops after $\frac{n^{2}}{2n - 1}$ identical planks
If a bullet’s speed falls to $u/n$ after penetrating a distance $x$ , it goes a further $\frac{x}{n^{2} - 1}$ before stopping

What this chapter covers

Position, displacement and distance
Velocity and acceleration
Equations of uniformly accelerated motion
Motion graphs
Free fall
Relative velocity

How it is usually asked

Apply the equations of motion
Read displacement or acceleration from a graph
Free-fall problems
Relative velocity in one dimension

Understanding Motion in a Straight Line

In one dimension, position is measured from a chosen origin along a line, and the sign tells you the direction. Displacement is the change in position, while distance is the total path length, so the two differ whenever the body turns back. Velocity is the rate of change of displacement and acceleration is the rate of change of velocity; both can be positive, negative or zero.

When acceleration is constant, three equations connect u, v, a, s and t: v = u + at, s = ut + ½at² and v² = u² + 2as. Free fall is the special case a = g directed downwards. Graphs carry the same information: the slope of an x–t graph is velocity, the slope of a v–t graph is acceleration, and the area under a v–t graph is displacement.

EAPCET questions usually combine one equation of motion with a unit conversion, a graph reading, the distance covered in the nth second, or a relative-velocity idea. Before choosing an equation, list the three known quantities and the one you want; each equation leaves out one of u, v, a, s and t, so pick the one that leaves out the quantity you neither know nor need.

Worked example

EAPCET-style question

A car moving at 72 km/h is brought to rest with uniform retardation in 4 s. The distance it covers while stopping is

(1)40 m
(2)80 m
(3)144 m
(4)20 m

Solution

Convert the speed: $72\ \text{km/h} = 72 \times \tfrac{5}{18} = 20\ \text{m/s}$ .
Retardation: $a = \frac{0 - 20}{4} = -5\ \text{m/s}^{2}$ .
Use $v^{2} = u^{2} + 2as$ : $0 = 20^{2} + 2(-5)s$ .
$s = 400/10 = 40\ \text{m}$ (check: average speed $10\ \text{m/s} \times 4\ \text{s} = 40\ \text{m}$ ).

Answer: 40 m

Shortcuts and results to remember

For uniform acceleration, average velocity $= \frac{u + v}{2}$ , so you can skip the area calculation on a straight-line v–t graph.
The equations of motion need constant acceleration; when a body reverses direction, split the motion at the turning point ( $v = 0$ ) to find distance.
For two bodies in free fall, relative acceleration is zero, so time to meet = separation / relative velocity.
If a stone is dropped and another is thrown down with speed $u$ from the same point $x$ seconds later, and both land together: $\tfrac{1}{2}gt^{2} = u(t - x) + \tfrac{1}{2}g(t - x)^{2}$ .

Common mistakes to avoid

Using speeds in km/h inside the equations of motion — multiply by 5/18 to convert to m/s first.
Treating distance and displacement as equal when the body reverses direction — split the motion at the point where v = 0.
Taking g as positive for an upward-thrown body while also taking upward as positive — with upward positive, a = −g.
Applying the constant-acceleration equations when acceleration varies with time — integrate a(t) or use the graph instead.

How to prepare it

Fix a sign convention at the start and keep it — most errors in this chapter are sign errors.

Once the formulas feel familiar, test them the way the exam does: practise Motion in a Straight Line questions chapter-wise, then attempt a full previous year paper to see whether it holds up under a 3-hour timer.

Related Physics chapters

See every chapter in the EAPCET Physics syllabus.

Practise Motion in a Straight Line chapter-wise

Chapter-wise quizzes show exactly which topics in this chapter you still get wrong — before a full paper does.

Frequently asked questions

Is Motion in a Straight Line part of the EAPCET Physics syllabus?: Yes. Motion in a Straight Line is taught in Intermediate first year Physics, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.
How should I prepare Motion in a Straight Line for EAPCET?: Fix a sign convention at the start and keep it — most errors in this chapter are sign errors.
How many Physics questions are there in EAPCET?: 40 of the 160 questions in the Engineering paper are Physics, spread across 30 chapters.
What mistakes do students make in Motion in a Straight Line?: Using speeds in km/h inside the equations of motion — multiply by 5/18 to convert to m/s first. Treating distance and displacement as equal when the body reverses direction — split the motion at the point where v = 0. Taking g as positive for an upward-thrown body while also taking upward as positive — with upward positive, a = −g. Applying the constant-acceleration equations when acceleration varies with time — integrate a(t) or use the graph instead.