Qus : 1
AMU MCA PYQ
1
The shortest distance from the point $(1,0,-2)$ to the plane
$x+2y+z=4$ is
1
$\frac{5\sqrt6}{6}$ 2
$\frac{5}{6}$ 3
$\frac{\sqrt6}{6}$ 4
$5\sqrt6$ Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2020 PYQ
Solution Distance formula:
$d=\frac{|ax_1+by_1+cz_1-d|}{\sqrt{a^2+b^2+c^2}}$
Plane: $x+2y+z-4=0$
$d=\frac{|1(1)+2(0)+1(-2)-4|}{\sqrt{1^2+2^2+1^2}}$
$=\frac{|1-2-4|}{\sqrt6}=\frac{5}{\sqrt6}
=\frac{5\sqrt6}{6}$
Qus : 2
AMU MCA PYQ
1
Two bodies of mass 100 g and 20 g are moving with velocities
$(2\hat{i}-7\hat{j}+3\hat{k})$ cm/s and $(-10\hat{i}+35\hat{j}-3\hat{k})$ cm/s respectively.
What is the velocity of centre of mass of this two body system?
1
$2\hat{i}$ cm/s 2
$(10\hat{i}+9\hat{j}-4\hat{k})$ cm/s 3
$(4\hat{i}-5\hat{j})$ cm/s 4
$3\hat{j}$ cm/s Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2020 PYQ
Solution Velocity of centre of mass:
$\vec{V}=\frac{m_1\vec{v}_1+m_2\vec{v}_2}{m_1+m_2}$
$=\frac{100(2\hat{i}-7\hat{j}+3\hat{k})+20(-10\hat{i}+35\hat{j}-3\hat{k})}{120}$
$=\frac{(200-200)\hat{i}+(-700+700)\hat{j}+(300-60)\hat{k}}{120}$
$=\frac{240\hat{k}}{120}=2\hat{k}$
Qus : 5
AMU MCA PYQ
4
If the centre of mass of three particles of masses 10, 20 and 30 gram be at the point $(1,-2,3)$, where should a fourth particle of 40 gram be placed so that the combined centre of mass may be $(1,1,1)$ ?
1
$(-1,5.5,2)$ 2
$(1,-5.5,2)$ 3
$(1,5.5,2)$ 4
$(1,5.5,-2)$ Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2022 PYQ
Solution
Qus : 6
AMU MCA PYQ
4
Which of the following is a 2-dimensional subspace of $\mathbb{R}^3$?
1
${(0,x,0)\mid x\in\mathbb{R}}$ 2
${(0,x,0)\mid x\in\mathbb{R}}\cup{(0,0,y)\mid y\in\mathbb{R}}$ 3
${(x,y,0)\mid x,y\in\mathbb{R},;x\ne y}$ 4
${(0,x,z)\mid x,z\in\mathbb{R}}$ Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2025 PYQ
Solution Set ${(0,x,z)}$ contains two independent parameters and satisfies subspace properties.
Qus : 8
AMU MCA PYQ
2
Let $\mathbb{R}^3={(x,y,z)}$ and $W$ be the subspace generated by ${(1,2,-3)}$. Geometrically, $W$ represents
1
a straight line having equation $2x-y=0=3y+2z$ 2
a straight line through origin with direction cosines $\frac{1}{\sqrt{14}},\frac{2}{\sqrt{14}},\frac{-3}{\sqrt{14}}$ 3
a plane $5x+2y+3z=0$ 4
a plane through given points Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2021 PYQ
Solution Single vector span ⇒ line through origin
Direction ratios: $1,2,-3$
Direction cosines:
$\frac{1}{\sqrt{14}},\frac{2}{\sqrt{14}},\frac{-3}{\sqrt{14}}$
Qus : 9
AMU MCA PYQ
3
A particle of mass 2 kg is moving such that its position is given by
$P(t)=5\hat{i}-2t^2\hat{j}$
Find angular momentum at $t=2$ sec about origin.
1
$64\hat{k}$ 2
$-64\hat{k}$ 3
$-80\hat{k}$ 4
$80\hat{k}$ Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2021 PYQ
Solution Position at $t=2$:
$\vec{r}=5\hat{i}-8\hat{j}$
Velocity:
$\vec{v}=\frac{d\vec{r}}{dt}=-4t\hat{j}$
At $t=2$:
$\vec{v}=-8\hat{j}$
Momentum:
$\vec{p}=m\vec{v}=2(-8\hat{j})=-16\hat{j}$
Angular momentum:
$\vec{L}=\vec{r}\times\vec{p}$
$=(5\hat{i}-8\hat{j})\times(-16\hat{j})$
$= -80\hat{k}$
Qus : 12
AMU MCA PYQ
3
The direction cosines of the line which is equally inclined to the axes is
1
$\pm1, \pm1, \pm1$ 2
$\pm\frac{1}{\sqrt{3}}, \pm\frac{2}{\sqrt{3}}, \pm\sqrt{3}$ 3
$\pm\frac{1}{\sqrt{3}}, \pm\frac{1}{\sqrt{3}}, \pm\frac{1}{\sqrt{3}}$ 4
$\pm\sqrt{3}, \pm\frac{\sqrt{3}}{2}, \pm\frac{1}{\sqrt{3}}$ Go to Discussion
AMU MCA Previous Year PYQ
AMU MCA AMU MCA 2020 PYQ
Solution If equally inclined then $l = m = n$
$l^2 + m^2 + n^2 = 1$
$3l^2 = 1$
$l = \pm\frac{1}{\sqrt{3}}$
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