1
A-II, B-III, C-I, D-IV 2
A-III, B-IV, C-II, D-I 3
A-IV, B-III, C-II, D-I 4
A-IV, B-III, C-I, D-II Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution Dog causes Rabies, Mosquito causes Malaria → A-IV
Amnesia affects Memory, Paralysis affects Movement → B-III
Meningitis affects Brain, Cirrhosis affects Liver → C-II
Influenza is caused by Virus, Typhoid is caused by Bacteria → D-I
Correct matching: A-IV, B-III, C-II, D-I
Qus : 5
CUET PYQ
4
$\vec a = 2\hat i + 2\hat j + 3\hat k,; \vec b = -\hat i + 2\hat j + \hat k$
and
$\vec c = 3\hat i + \hat j$
are such that $\vec a + \gamma \vec b$ is perpendicular to $\vec c$, then determine the value of $\gamma$.
1
3
2
0 3
4 4
8 Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution Perpendicular condition:
$(\vec a + \gamma \vec b)\cdot \vec c = 0$
$\vec a + \gamma \vec b = (2-\gamma)\hat i + (2+2\gamma)\hat j + (3+\gamma)\hat k$
$\vec c = 3\hat i + \hat j$
Dot product:
$3(2-\gamma) + 1(2+2\gamma) = 0$
$6 - 3\gamma + 2 + 2\gamma = 0$
$8 - \gamma = 0 \Rightarrow \gamma = 8$
Qus : 6
CUET PYQ
2
If $\vec{a}$ and $\vec{b}$ are two unit vectors such that $\vec{a}+2\vec{b}$ and $5\vec{a}-4\vec{b}$ are perpendicular to each other, then the angle between $\vec{a}$ and $\vec{b}$ is:
1
$45{^{\circ}}$ 2
$60{^{\circ}}$ 3
${\cos }^{-1}\Bigg{(}\frac{1}{3}\Bigg{)}$ 4
${\cos }^{-1}\Bigg{(}\frac{2}{7}\Bigg{)}$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2022 PYQ
Solution
Solution:
Given two unit vectors \( \vec{a} \) and \( \vec{b} \), and the vectors \( \vec{a} + 2\vec{b} \) and \( 5\vec{a} - 4\vec{b} \) are perpendicular, we use the condition for perpendicular vectors:
$$ (\vec{a} + 2\vec{b}) \cdot (5\vec{a} - 4\vec{b}) = 0 $$
Expanding the dot product:
$$ (\vec{a} + 2\vec{b}) \cdot (5\vec{a} - 4\vec{b}) = \vec{a} \cdot 5\vec{a} + \vec{a} \cdot (-4\vec{b}) + 2\vec{b} \cdot 5\vec{a} + 2\vec{b} \cdot (-4\vec{b}) $$
Using properties of dot products and knowing \( \vec{a} \) and \( \vec{b} \) are unit vectors (\( \vec{a} \cdot \vec{a} = 1 \) and \( \vec{b} \cdot \vec{b} = 1 \)):
$$ 5(\vec{a} \cdot \vec{a}) - 4(\vec{a} \cdot \vec{b}) + 10(\vec{b} \cdot \vec{a}) - 8(\vec{b} \cdot \vec{b}) = 0 $$
Simplifying:
$$ 5(1) - 4(\vec{a} \cdot \vec{b}) + 10(\vec{a} \cdot \vec{b}) - 8(1) = 0 $$
$$ 5 - 8 + 6(\vec{a} \cdot \vec{b}) = 0 $$
$$ -3 + 6(\vec{a} \cdot \vec{b}) = 0 $$
$$ 6(\vec{a} \cdot \vec{b}) = 3 $$
$$ \vec{a} \cdot \vec{b} = \frac{1}{2} $$
The dot product \( \vec{a} \cdot \vec{b} = \cos \theta \), where \( \theta \) is the angle between \( \vec{a} \) and \( \vec{b} \):
$$ \cos \theta = \frac{1}{2} $$
Therefore, the angle \( \theta \) is:
$$ \theta = \cos^{-1} \left( \frac{1}{2} \right) = 60^\circ $$
Final Answer:
$$ \boxed{60^\circ} $$
Qus : 7
CUET PYQ
2
Let $\vec{a}=\hat{i}-\hat{j}$ and $\vec{b}=\hat{i}+\hat{j}+\hat{k}$ and $\vec{c}$ be a vector such that $(\vec{a} \times \vec{c})+\vec{b}=0$ and $\vec{a}.\vec{c}=4$, then $|\vec{c}|^2$ is equal to
1
$8$ 2
$\frac{19}{2}$ 3
$9$ 4
$\frac{17}{2}$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2022 PYQ
Solution
Solution:
Given vectors:
\(\vec{a} = \hat{i} - \hat{j}\)
\(\vec{b} = \hat{i} + \hat{j} + \hat{k}\)
And \((\vec{a} \times \vec{c}) + \vec{b} = 0\)
\(\vec{a} \cdot \vec{c} = 4\)
From \((\vec{a} \times \vec{c}) + \vec{b} = 0\), we get:
\[
\vec{a} \times \vec{c} = -\vec{b}
\]
Let \(\vec{c} = x\hat{i} + y\hat{j} + z\hat{k}\).
The cross product \(\vec{a} \times \vec{c}\) is:
\[
\vec{a} \times \vec{c} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 1 & -1 & 0 \\ x & y & z \end{vmatrix}
\]
Expanding this determinant:
\[
\vec{a} \times \vec{c} = (z \hat{i} + z \hat{j} + (x + y) \hat{k})
\]
Setting \(\vec{a} \times \vec{c} = -\vec{b}\), we get:
\[
z = -1, \quad z = -1, \quad x + y = -1
\]
Therefore:
\[
x + y = -1
\]
Now, from \(\vec{a} \cdot \vec{c} = 4\):
\[
\vec{a} \cdot \vec{c} = 1 \cdot x + (-1) \cdot y = 4
\]
Simplifying:
\[
x - y = 4
\]
Solving the system of equations:
\[
x + y = -1
\]
\[
x - y = 4
\]
Adding the two equations:
\[
2x = 3 \quad \Rightarrow \quad x = \frac{3}{2}
\]
Substituting into \(x + y = -1\):
\[
\frac{3}{2} + y = -1 \quad \Rightarrow \quad y = -\frac{5}{2}
\]
Now, \(\vec{c} = \frac{3}{2} \hat{i} - \frac{5}{2} \hat{j} - \hat{k}\).
To find \(|\vec{c}|^2\), we compute:
\[
|\vec{c}|^2 = \left( \frac{3}{2} \right)^2 + \left( -\frac{5}{2} \right)^2 + (-1)^2 = \frac{9}{4} + \frac{25}{4} + 1
\]
\[
|\vec{c}|^2 = \frac{9 + 25 + 4}{4} = \frac{38}{4} = 9.5
\]
Final Answer:
$$ \boxed{9.5} $$
Qus : 8
CUET PYQ
1
If the unit vectors $\vec a$ and $\vec b$ are inclined at an angle $2\theta$ such that
$|\vec a - \vec b| < 1$ and $0 \le \theta \le \pi$, then $\theta$ lies in the interval
1
$\left[0,\dfrac{\pi}{2}\right]$ 2
$\left[\dfrac{5\pi}{6},\pi\right]$ 3
$\left[\dfrac{\pi}{6},\dfrac{\pi}{2}\right]$ 4
$\left[\dfrac{\pi}{2},\dfrac{5\pi}{6}\right]$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution $|\vec a - \vec b| = \sqrt{2-2\cos 2\theta}$
Given:
$\sqrt{2-2\cos 2\theta} < 1$
Squaring:
$2-2\cos 2\theta < 1$
$\cos 2\theta > \dfrac{1}{2}$
So,
$0 \le 2\theta < \dfrac{\pi}{3}$
$\Rightarrow 0 \le \theta < \dfrac{\pi}{6}$
From given options, valid interval is included in
$\left[0,\dfrac{\pi}{2}\right]$
Qus : 9
CUET PYQ
4
If $\vec{a}$, $\vec{b}$, $\vec{c}$ and $\vec{d}$ are the unit vectors such that $(\vec{a} \times \vec{b}).(\vec{c} \times \vec{d})=1$ and $(\vec{a}.\vec{c})=\frac{1}{2}$, then
1
Only $\vec{a}, \vec{b}, \vec{c}$ are non -coplanar 2
Only $\vec{a}, \vec{b}, \vec{d}$ are non -coplanar 3
Both $\vec{a}, \vec{b}, \vec{c}$ and $\vec{a}, \vec{b}, \vec{d}$ are non -coplanar 4
Both $\vec{a}, \vec{b}, \vec{c}$ and $\vec{a}, \vec{b}, \vec{d}$ are coplanar Go to Discussion
CUET Previous Year PYQ
CUET CUET 2022 PYQ
Solution
Qus : 10
CUET PYQ
4
The moment of the couple formed by the forces
$5\hat i+\hat k$ and $-5\hat i-\hat k$ acting at the points $(9,-1,2)$ and $(3,-2,1)$ respectively is
1
$11\hat i-\hat j+5\hat k$ 2
$-\hat i+11\hat j-5\hat k$ 3
$-\hat i+11\hat j+5\hat k$ 4
$\hat i-\hat j-5\hat k$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution Moment of a couple $=\vec r \times \vec F$
$\vec r=(9,-1,2)-(3,-2,1)=(6,1,1)$
$\vec F=5\hat i+\hat k$
$\vec M=\begin{vmatrix}
\hat i & \hat j & \hat k \
6 & 1 & 1 \
5 & 0 & 1
\end{vmatrix}
= \hat i(1-0)-\hat j(6-5)+\hat k(0-5)$
$=\hat i-\hat j-5\hat k$
Qus : 11
CUET PYQ
1
If $\oplus$ and $\odot$ denote exclusive OR and exclusive NOR operations respectively, then which one of the following is not correct?
1
$P\oplus Q=P\odot Q$ 2
$\bar P\oplus Q=P\odot Q$ 3
$\bar P\oplus\bar Q=P\oplus Q$ 4
$(P\oplus\bar P)+Q=(P\odot\bar P)\odot Q$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution XOR and XNOR are complements of each other.
Statement (1) claims them equal, which is false.
Qus : 12
CUET PYQ
1
Each of the angle between vectors $\vec a$, $\vec b$ and $\vec c$ is equal to $60^\circ$.
If $|\vec a|=4$, $|\vec b|=2$ and $|\vec c|=6$, then the modulus of
$\vec a+\vec b+\vec c$ is
1
$10$ 2
$15$ 3
$12$ 4
$20$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution $|\vec a+\vec b+\vec c|^2
= a^2+b^2+c^2
+2(\vec a\cdot\vec b+\vec b\cdot\vec c+\vec c\cdot\vec a)$
Since angle $=60^\circ$,
$\vec a\cdot\vec b=|a||b|\cos60^\circ=\dfrac{ab}{2}$
So,
$=16+4+36+2\left(\dfrac{4\cdot2+2\cdot6+6\cdot4}{2}\right)$
$=56+44=100$
$\Rightarrow |\vec a+\vec b+\vec c|=10$
Qus : 15
CUET PYQ
1
Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A:
If dot product and cross product of vectors $\vec A$ and $\vec B$ are zero, it implies that one of the vectors $\vec A$ or $\vec B$ must be a null vector.
Reason R:
Null vector is a vector with zero magnitude.
Choose the correct answer:
1
Both A and R are true and R is the correct explanation of A 2
Both A and R are true but R is not the correct explanation of A 3
A is true but R is false 4
A is false but R is true Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution $\vec A\times\vec B=0$ ⇒ vectors are parallel
A non-zero vector cannot be both parallel and perpendicular
⇒ one vector must be zero
✔ Assertion A is true
✔ Reason R is true
✔ R explains A
Qus : 16
CUET PYQ
1
LIST I LIST II A. $|\vec A+\vec B|=|\vec A-\vec B|$ I. $45^\circ$ B. $|\vec A\times\vec B|=\vec A\cdot\vec B$ II. $30^\circ$ C. $|\vec A\cdot\vec B|=\dfrac{AB}{2}$ III. $90^\circ$ D. $|\vec A\times\vec B|=\dfrac{AB}{2}$ IV. $60^\circ$
1
A-III, B-I, C-IV, D-II 2
A-III, B-II, C-IV, D-IV 3
A-III, B-I, C-II, D-IV 4
A-II, B-I, C-III, D-IV Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution A:
$|\vec A+\vec B|=|\vec A-\vec B| \Rightarrow \vec A\cdot\vec B=0$
$\Rightarrow$ angle $=90^\circ$ → III
B:
$|\vec A\times\vec B|=\vec A\cdot\vec B$
$AB\sin\theta=AB\cos\theta \Rightarrow \theta=45^\circ$ → I
C:
$|\vec A\cdot\vec B|=AB\cos\theta=\dfrac{AB}{2}$
$\Rightarrow \cos\theta=\dfrac12 \Rightarrow \theta=60^\circ$ → IV
D:
$|\vec A\times\vec B|=AB\sin\theta=\dfrac{AB}{2}$
$\Rightarrow \sin\theta=\dfrac12 \Rightarrow \theta=30^\circ$ → II
Correct Matching:
A-III, B-I, C-IV, D-II
Qus : 17
CUET PYQ
1
If $\hat n_1,\hat n_2$ are two unit vectors and $\theta$ is the angle between them, then $\cos\dfrac{\theta}{2}$ is equal to
1
$\dfrac12|\hat n_1+\hat n_2|$ 2
$\dfrac12|\hat n_1-\hat n_2|$ 3
$\dfrac12|\hat n_1\cdot\hat n_2|$ 4
$\dfrac{|\hat n_1\times\hat n_2|}{2|\hat n_1||\hat n_2|}$ Go to Discussion
CUET Previous Year PYQ
CUET CUET 2023 PYQ
Solution $|\hat n_1+\hat n_2|^2=2(1+\cos\theta)$
So,
$|\hat n_1+\hat n_2|=2\cos\dfrac{\theta}{2}$
Hence,
$\cos\dfrac{\theta}{2}=\dfrac12|\hat n_1+\hat n_2|$
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