The velocity-time graph of an object moving along a straight line is shown in figure. What is the distance covered by the object between t = 0 to t = 4s ?
Velocity Time Graphs diagram for Q9 - JEE Main 2025 Evening
The velocity-time profile tracking motion across consecutive geometric shapes up to 4 seconds.

Solution & Explanation

Related Formula

The distance traveled by an object equals the total area enclosed under its velocity-time (v-t) plot along the time axis, treating all regional boundaries as strictly positive metrics:

Distance = ∫ |v| dt
Core Logic

From the geometric grid profile between t = 0 and t = 4 s:

  • First Region (t=0 to t=2 s): Forms a \right-angled \triangle with base = 2 s and peak height = 10 ms⁻¹.
Area₁ = (1)/(2) × 2 × 10 = 10 m
  • Second Region (t=2 to t=4 s): Forms a standard rectangle with width = (4 - 2) = 2 s and height = 10 ms⁻¹.
Area₂ = 2 × 10 = 20 m

Summing the areas together to extract total displacement path:

Total Distance = 10 + 20 = 30 m
Pattern Recognition

Always differentiate between distance and displacement on graph tracks. Displacement treats components below the axis as negative fields, while distance calculates absolute geometric magnitudes without direction.

Chapter Mix

Class 11 Physics: Motion in a Straight Line

Reference Study Guides

More Motion in a Straight Line Previous-Year Questions — Page 8

Q44 jee_main_2024_31_jan_evening Vector Algebra
If two vectors A and B having equal magnitude R are inclined at an angle θ, then
  • A. | A - B| = √(2)R ((θ)/(2))
  • B. | A + B| = 2R ((θ)/(2))
  • C. | A + B| = 2R ((θ)/(2))
  • D. | A - B| = 2R ((θ)/(2))

Solution

Related Formula

The magnitude of the resultant vector is given by:

| Rᵣₑₛ| = √(A² + B² + 2AB θ)
Core Logic

Let | A| = | B| = R. Then for vector addition:

| A + B| = √(R² + R² + 2R² θ)
Step 1: Simplify Addition Form
| A + B| = √(2R² (1 + θ))

Using the trigonometric identity 1 + θ = 2 ² ((θ)/(2)):

| A + B| = √(2R² × 2 ² ((θ)/(2))) = 2R ((θ)/(2))
Step 2: Cross-check Subtraction Form

For subtraction:

| A - B| = √(R² + R² - 2R² θ) | A - B| = √(2R² (1 - θ)) = √(2R² × 2 ² ((θ)/(2))) = 2R ((θ)/(2))

Checking options, only | A + B| = 2R ((θ)/(2)) is correctly paired in the choice list.

Pattern Recognition

Standard geometry shortcut: Addition of two equal vectors yields a cosine half-angle dependency. Subtraction yields a sine half-angle dependency. (+ → ), (- → ).

Chapter Mix

Class 11 Physics: Motion in a Plane

Q jee_main_2024_31_jan_morning Projectile Motion
A body starts falling freely from height H hits an inclined plane in its path at height h. As a result of this perfectly elastic impact, the direction of the velocity of the body becomes horizontal. The value of (H)/(h) for which the body will take the maximum time to reach the ground is
Numerical Answer. Answer: 2 to 2

Solution

Related Formula
t = √((2d)/(g))
Core Logic

Projectile Motion diagram for Q55 - JEE Main 2024 Morning
Projectile Motion diagram for Q55 - JEE Main 2024 Morning

The body falls freely from height H to height h. The distance fallen is (H - h). Time taken to fall this distance:

t₁ = √((2(H - h))/(g))

After elastic impact, the vertical velocity becomes zero (the entire velocity is directed horizontally). From height h, it now acts as a horizontal projectile. The time taken to reach the ground vertically from height h is:

t₂ = √((2h)/(g))

Total time of flight T = t₁ + t₂:

T = √((2(H - h))/(g)) + √((2h)/(g))
Step 2: Maximizing Time

To find the maximum time T, differentiate T with respect to h and equate to zero:

(dT)/(dh) = √((2)/(g)) ( -12√(H - h) + 12√(h) ) = 0 12√(h) = 12√(H - h) √(H - h) = √(h)

Squaring both sides: H - h = h H = 2h

(H)/(h) = 2
Chapter Mix

Class 11 Physics: Kinematics

Q33 jee_main_2024_31_jan_morning Differentiation In Kinematics
The relation between time 't' and distance 'x' is t = α x² + β x, where α and β are constants. The relation between acceleration (a) and velocity (v) is:
  • A. a = -2α v³
  • B. a = -5α v⁵
  • C. a = -3α v²
  • D. a = -4α v⁴

Solution

Related Formula
v = (dx)/(dt) a = (dv)/(dt) = v(dv)/(dx)
Step 1: Differentiate with respect to time

Given the equation:

t = α x² + β x

Differentiating with respect to time t:

(dt)/(dt) = (d)/(dt)(α x² + β x) 1 = 2α x (dx)/(dt) + β (dx)/(dt) 1 = (2α x + β) v v = (2α x + β)⁻¹
Step 2: Calculate Acceleration

Now, acceleration a = (dv)/(dt). Differentiating v with respect to time t:

a = (d)/(dt) [ (2α x + β)⁻¹ ] a = -1(2α x + β)⁻² · (d)/(dt)(2α x + β) a = -(2α x + β)⁻² · (2α) (dx)/(dt)

Substitute v and (2α x + β)⁻² = v²:

a = -(v²) · (2α) · v a = -2α v³
Pattern Recognition

Standard kinematic shortcut: Whenever t = Ax² + Bx, v = (2Ax+B)⁻¹ and a = -2A v³. Memorizing this directly saves derivation time during the exam.

Chapter Mix

Class 11 Physics: Kinematics

More Motion in a Straight Line Questions — jee_main_2025_28_jan_evening

Practice all Motion in a Straight Line previous-year questions →

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