INTERMEDIATE PHYSICS – LESSON 3
MOTION IN A PLANE
STAGE–2 : IMPORTANT QUESTIONS & NUMERICALS
🔹 A. VERY SHORT ANSWER QUESTIONS (2 MARKS)
Q1. What is motion in a plane?
Motion in which a body moves in two dimensions simultaneously is called motion in a plane.
Q2. Define scalar quantity.
A physical quantity which has only magnitude and no direction is called a scalar quantity.
Q3. Define vector quantity.
A physical quantity which has both magnitude and direction is called a vector quantity.
Q4. What is a position vector?
The vector drawn from the origin to the position of a particle is called the position vector.
Q5. What is projectile motion?
The motion of a body projected into air and moving under the influence of gravity alone is called projectile motion.
🔹 B. SHORT ANSWER QUESTIONS (4 MARKS)
Q1. Distinguish between scalar and vector quantities.
| Scalar | Vector |
|---|---|
| Has only magnitude | Has magnitude and direction |
| Added algebraically | Added vectorially |
| Example: speed | Example: velocity |
Q2. Explain position vector and displacement vector.
The position vector represents the position of a particle with respect to the origin. The displacement vector represents the change in position of the particle.
Q3. What is relative velocity?
The velocity of one body with respect to another body is called relative velocity.
🔹 C. LONG ANSWER QUESTIONS (8 MARKS)
Q1. Explain projectile motion.
Projectile motion is the motion of a body projected into air and moving under gravity.
- The horizontal motion is uniform
- The vertical motion is uniformly accelerated
- The path followed is parabolic
Horizontal and vertical motions are independent of each other.
Q2. Derive expressions for horizontal and vertical displacement of a projectile.
Horizontal displacement:
x = u cosθ · t
Vertical displacement:
y = u sinθ · t − ½gt²
🔹 D. NUMERICAL PROBLEMS (VERY IMPORTANT)
Numerical 1: A projectile is thrown horizontally with a velocity of 10 m/s. Find the horizontal distance travelled in 2 s.
Solution:
Horizontal distance = u × t
= 10 × 2 = 20 m
Numerical 2: Find the horizontal and vertical components of velocity 20 m/s making an angle of 30° with horizontal.
Solution:
vx = v cosθ = 20 × cos30° = 17.32 m/s
vy = v sinθ = 20 × sin30° = 10 m/s
Numerical 3: Two trains move in the same direction with speeds 40 km/h and 60 km/h. Find the relative velocity.
Solution:
Relative velocity = 60 − 40 = 20 km/h
🎯 INTERMEDIATE EXAM TIPS
- Always draw neat diagrams for projectile motion
- Write formulas clearly before substitution
- Vector questions are scoring if diagram is drawn
- Numericals are easy marks – practice daily
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