Grade 11 : Physics - Motion (Straight/Plane) (Set 1) | Concept of Maths

Question 1

1. A delivery drone travels along a semi-circular path of radius $R = 14$ meters. If the drone moves from point A to point B (diametrically opposite), what is the magnitude of its displacement?

A) $14\text{ m}$

B) $28\text{ m}$

C) $44\text{ m}$

D) $88\text{ m}$

Answer

Correct Answer: B

Displacement is the shortest distance between the initial and final positions. For a semi-circular path, the distance between diametrically opposite points is the diameter. $$\text{Displacement} = 2R = 2 \times 14 = 28\text{ m}$$

Question 2

2. A high-speed train is traveling at a constant speed of $108\text{ km/h}$. What is its speed in meters per second ($\text{m/s}$)?

A) $20\text{ m/s}$

B) $25\text{ m/s}$

C) $30\text{ m/s}$

D) $35\text{ m/s}$

Answer

Correct Answer: C

To convert $\text{km/h}$ to $\text{m/s}$, multiply by $$\frac{5}{18}$$. $$108 \times \frac{5}{18} = 6 \times 5 = 30\text{ m/s}$$

Question 3

3. The speedometer of a moving car measures which of the following physical quantities?

A) Instantaneous speed

B) Average speed

C) Instantaneous velocity

D) Average velocity

Answer

Correct Answer: A

A speedometer indicates the speed of the vehicle at that specific moment in time, which is the instantaneous speed. It does not show direction, so it is not velocity.

Question 4

Question 5

5. In a velocity-time ($v-t$) graph, what does the area under the curve represent?

A) Acceleration

B) Speed

C) Jerk

D) Displacement

Answer

Correct Answer: D

The area under a velocity-time graph represents the change in position, which is the displacement of the object.

Question 6

6. A ball is thrown vertically upwards with an initial velocity $u$. At the highest point of its trajectory, its velocity is:

A) $u$

B) $0$

C) $g$

D) $2u$

Answer

Correct Answer: B

When an object is thrown upwards, it slows down due to gravity until it momentarily stops at the peak before falling back down. Thus, the velocity at the highest point is $0$.

Question 7

7. A hiker walks $3\text{ km}$ towards the North and then $4\text{ km}$ towards the East. What is the magnitude of the hiker's total displacement?

A) $5\text{ km}$

B) $7\text{ km}$

C) $1\text{ km}$

D) $12\text{ km}$

Answer

Correct Answer: A

The two paths are perpendicular. Using Pythagoras' theorem: $$\text{Displacement} = \sqrt{3^2 + 4^2} = \sqrt{9 + 16} = \sqrt{25} = 5\text{ km}$$

Question 8

8. Which of the following is a scalar quantity?

A) Displacement

B) Distance

C) Velocity

D) Acceleration

Answer

Correct Answer: B

Scalar quantities have only magnitude and no direction. Distance is a scalar, whereas displacement, velocity, and acceleration are all vectors.

Question 9

9. If an object is moving with constant velocity, its acceleration is:

A) Increasing

B) Decreasing

C) Zero

D) Constant but non-zero

Answer

Correct Answer: C

Acceleration is defined as the rate of change of velocity ($a = \frac{dv}{dt}$). If velocity is constant, the change in velocity is zero, hence acceleration is zero.

Question 10

10. For a projectile fired from the ground, at what angle $\theta$ (relative to the horizontal) is the horizontal range maximum?

A) $45^\circ$

B) $30^\circ$

C) $60^\circ$

D) $90^\circ$

Answer

Correct Answer: A

The horizontal range is given by $R = \frac{u^2 \sin(2\theta)}{g}$. Range is maximum when $\sin(2\theta) = 1$, which occurs when $2\theta = 90^\circ$, or $\theta = 45^\circ$.

Question 11

11. Car A moves at $60\text{ km/h}$ and Car B moves at $40\text{ km/h}$ in the same direction. What is the velocity of Car A relative to Car B?

A) $100\text{ km/h}$

B) $20\text{ km/h}$

C) $50\text{ km/h}$

D) $0\text{ km/h}$

Answer

Correct Answer: B

When moving in the same direction, relative velocity is the difference: $$V_{AB} = V_A - V_B = 60 - 40 = 20\text{ km/h}$$

Question 12

12. A stone is dropped from a tower of height $H$. Ignoring air resistance, the time taken to reach the ground is proportional to:

A) $H$

B) $H^2$

C) $1/H$

D) $\sqrt{H}$

Answer

Correct Answer: D

Using $H = \frac{1}{2}gt^2$, we get $t = \sqrt{\frac{2H}{g}}$. Therefore, $t \propto \sqrt{H}$.

Question 13

13. The slope of a position-time ($x-t$) graph represents:

A) Velocity

B) Acceleration

C) Displacement

D) Force

Answer

Correct Answer: A

The slope of the position-time graph is $\frac{dx}{dt}$, which is defined as velocity.

Question 14

14. A particle moves in a circle of radius $r$ with constant speed $v$. The magnitude of its acceleration is:

A) $0$

B) $v/r$

C) $v^2/r$

D) $vr$

Answer

Correct Answer: C

In uniform circular motion, even though the speed is constant, the direction of velocity changes, leading to centripetal acceleration $a_c = \frac{v^2}{r}$.

Question 15

15. Which of the following can never be negative?

A) Velocity

B) Distance

C) Displacement

D) Acceleration

Answer

Correct Answer: B

Distance is the actual path length traveled and is always a non-negative scalar quantity. Displacement, velocity, and acceleration are vectors and can be negative depending on the chosen coordinate system.

Question 16

16. A particle starts from rest and moves with constant acceleration. The ratio of distances covered in $1\text{ s}$, $2\text{ s}$, and $3\text{ s}$ is:

A) $1:2:3$

B) $1:4:9$

C) $1:3:5$

D) $1:1:1$

Answer

Correct Answer: B

Distance $s = \frac{1}{2}at^2$. For $t=1$, $s_1 = \frac{1}{2}a(1)^2 = 0.5a$. For $t=2$, $s_2 = \frac{1}{2}a(2)^2 = 2a$. For $t=3$, $s_3 = \frac{1}{2}a(3)^2 = 4.5a$. Ratio: $0.5 : 2 : 4.5 \Rightarrow 1 : 4 : 9$. (Note: $1:3:5$ is the ratio of distances in successive seconds, not total time).

Question 17

17. If the displacement of an object is zero, its distance traveled:

A) Must be zero

B) Cannot be zero

C) May or may not be zero

D) Is always negative

Answer

Correct Answer: C

If an object returns to its starting point, displacement is zero, but distance is the total path covered (e.g., one full lap around a track). If the object never moved, both are zero. Hence, it may or may not be zero.

Question 18

18. The horizontal component of velocity in projectile motion (neglecting air resistance) is:

A) Constant

B) Continuously increasing

C) Continuously decreasing

D) Zero at the highest point

Answer

Correct Answer: A

Since there is no horizontal force (ignoring air resistance), the horizontal acceleration is zero ($a_x = 0$), making the horizontal velocity constant throughout the flight.

Question 19

19. A body is moving with a constant speed of $5\text{ m/s}$ in a circle of radius $2\text{ m}$. What is the change in velocity when it describes a semi-circle?

A) $0\text{ m/s}$

B) $5\text{ m/s}$

C) $10\text{ m/s}$

D) $25\text{ m/s}$

Answer

Correct Answer: C

Velocity is a vector. At the start, let $v_1 = 5\hat{i}$. After a semi-circle, the direction is reversed, so $v_2 = -5\hat{i}$. $$\text{Change in velocity} = |v_2 - v_1| = |-5 - 5| = 10\text{ m/s}$$

Question 20

20. Which equation represents the third equation of motion?

A) $v = u + at$

B) $s = ut + \frac{1}{2}at^2$

C) $s = vt - \frac{1}{2}at^2$

D) $v^2 = u^2 + 2as$

Answer

Correct Answer: D

The three standard equations of motion are $v=u+at$, $s=ut+0.5at^2$, and $v^2=u^2+2as$. Option D is the third one.

Accepted Answer

Correct Answer: C

Using the equation of motion: $$s = ut + \frac{1}{2}at^2$$ Since it starts from rest, $u = 0$. $$s = 0 + \frac{1}{2}(4)(3)^2 = 2 \times 9 = 18\text{ m}$$

Grade 11 : Physics - Motion (Straight/Plane) (Set 1) | Concept of Maths