Q1: $90^\circ$ (orthogonal)
Q2: $120^\circ$
Q3: $\frac{4\hat{i} + 3\hat{j} + 2\hat{k}}{\sqrt{29}}$
Q4: $5$ units
Q5: $\frac{5}{\sqrt{2}}$
Q6: $a = 3$
Q7: $10\sqrt{2}$ m/s, NW
Q8: $0^\circ$ or $180^\circ$
Q9: $5 \text{ N}$ and $13 \text{ N}$
Q10: Proof ($\vec{B} = 2\vec{A}$)
Q11: $v=5, a=4$ m/s$^2$
Q12: $\vec{v}=12.8\hat{i}+3.6\hat{j}$, $\vec{r}=41.6\hat{i}+7.2\hat{j}$
Q13: $3t^2\sqrt{\alpha^2+\beta^2}$
Q14: $36 \text{ m}$ (at $t=6$)
Q15: $\vec{u}=10\hat{i}+20\hat{j}$, $a=-100\hat{j}$
Q16: $y = \frac{3x^2}{4} - x$
Q17: Proof ($\vec{r}\cdot\vec{v}=0$)
Q18: $3\sqrt{3}\text{s}, 33.75\text{m}, 45\sqrt{3}\text{m}$
Q19: $\tan^{-1}(4)$
Q20: Proof
Q21: $100 \text{ m}$
Q22: $20 \text{ m}$
Q23: $y = 2x - 5x^2$
Q24: $\tan^{-1}(4/3) = 53^\circ$
Q25: No ($R_{max}=3.46\text{km}$)
Q26: $u / (g \sin\theta)$
Q27: $v_0\sqrt{1+3\cos^2\theta}/2$
Q28: $60^\circ, 2\text{ m/s}$ (if g=10)
Q29: $0$, $-2u\sin\theta\hat{j}$
Q30: Proof
Q31: $E/2$
Q32: $14.14\text{s}, 7070\text{m}$
Q33: $45^\circ$
Q34: $17.3 \text{ m}$ (approx)
Q35: $25 \text{ m/s}$
Q36: $26.6 \text{ m}$
Q37: $\cot\alpha = 2\tan\theta$
Q38: Back in truck; Parabola
Q39: $ut(\sin\theta_1-\sin\theta_2)$
Q40: Same speed
Q41: $\tan^{-1}(1/3)$ South of Vert.
Q42: $3\sqrt{2}$ km/h, $45^\circ$
Q43: Due North, $10 \text{ s}$
Q44: $120^\circ$ to flow, $11.5 \text{ s}$
Q45: No; $\sin^{-1}(v_s/v_r)$ from vert.
Q46: $50\sqrt{2}\text{km}, 5\text{ hrs}$
Q47: $\sin^{-1}(150/800)$ South of East
Q48: $\sqrt{v_1^2+v_2^2}$
Q49: $8 \text{ km/h}$ at $30^\circ$
Q50: $50 \text{ rad/s}$
Q51: $16 \text{ rad/s}^2$
Q52: $2v, 2v^2/\pi R$
Q53: $\sqrt{4+10.24} = 3.77 \text{ m/s}^2$
Q54: Acute ($<90^\circ$), Obtuse ($>90^\circ$)
Q55: $8 \text{ N}$
Q56: $u^2\cos^2\theta / g$
Q57: $u^2 / (g\cos\theta)$
Q58: $\sqrt{2^2+2^2} = 2\sqrt{2} \text{ m/s}^2$
Q59: Proof via derivatives
Q60: Ellipse, $x^2/a^2+y^2/b^2=1$
Q61: Straight line
Q62: Yes, always hits.
Q63: $u\sqrt{2h/(g+a_0)}$
Q64: $b^2/2c$
Q65: $\sin 2\theta = \frac{x\sin 2\beta + y\sin 2\alpha}{x+y}$
Q66: $t_A = t_B$
Q67: $10 \text{ m}$ ($v^2/g = 100/10$)
Q68: $t_0 = -(\vec{v}_0\cdot\vec{a})/a^2$
Q69: $\sqrt{g(h+\sqrt{x^2+h^2})}$
Q70: $P = m k^2 r^2 t$