Class 11th

$a=\mu g=0.4*10=4m/s^2$

Slipping stops when V_bag = V_conveyar

0 + at = 2

t = $\frac{2}{a}=\frac{2}{4}=.5sec$ $\frac{}{}\frac{}{}$

So, x = $\frac{1}{2}a{t}^2=\frac{1}{2}*4*\frac{1}{4}=0.5m$

$P=\overrightarrow{F}.\overrightarrow{v}=v\frac{dP}{dt}=v^2\left(\frac{dm}{dt}\right)=0.5*25=12.5W$

$Torque\overrightarrow{\tau }=\overrightarrow{r}*\overrightarrow{F}$

$\left[\tau \right]=\left[L\right]\left[ML{T}^{-2}\right]$

$\left[\tau \right]=\left[M{L}^2{T}^{-2}\right]$

as, $\tau =m{\mathcal{l}}^2{t}^{-2}$

$\frac{d\tau }{\tau }*100=\left|\frac{dm}{m}*100\right|+2\left|\frac{d\mathcal{l}}{\mathcal{l}}*100\right|+2\left|\frac{dt}{t}*100\right|$

= 5 + 2 * 5 + 2 * 5

= 25 %

Let additional force is $\overrightarrow{F}$ , so

$\overrightarrow{F}+5\left(+\widehat{i}\right)+6\left(-\widehat{i}\right)+7\left(+\widehat{j}\right)+8\left(-\widehat{j}\right)=\overrightarrow{0}$

$\Rightarrow \overrightarrow{F}-\left(\widehat{i}+\widehat{j}\right)=\overrightarrow{0}\Rightarrow \overrightarrow{F}=\widehat{i}+\widehat{j}\Rightarrow F=\sqrt[]{2}N,45°$

$\Delta p$ = Change in momentum of each ball

$\Delta p=2mv=2*0.05*10=1Ns$

$\Rightarrow F=\frac{\Delta p}{\Delta t}=\frac{2*0.05*10}{0.005}=200N$

Since liquid drop is in equilibrium, so

mg = F_B + 2πRT

$\Rightarrow \frac{4}{3}\pi R^3\rho g=\frac{2}{3}\pi R^3\sigma g+2\pi RT$

$\Rightarrow R=\frac{3T}{\left(2\rho -\sigma \right)g}=\frac{15}{\sqrt[]{\left(2\rho -\sigma \right)}}*10^{-2}m=\frac{15}{\sqrt[]{\left(2\rho -\sigma \right)}}cm$

Total concentration of H⁺ after the mixing of HCl and H₂SO₄

$\left[H^{+}\right]=\frac{\left(200*0.01\right)+\left(400*2*0.01\right)}{600}$

$\left[H^{+}\right]=\frac{1}{60}$

$\therefore pH=lo{g}_{10}\left(\frac{1}{60}\right)=1.78$

Yes. Friction is a contact force that works against the relative motion between two surfaces. It can be static, which prevents motion. It can also be kinetic, which resists motion that's already happening. 

The four key contact forces that you will read in Class 11 Physics are normal force, friction, tension, and spring force. Each of these forces needs physical contact and follows Newton's Third Law. They come into play during motion, compression, stretching, or when objects rest on surfaces. These contact forces help in drawing the free-body diagrams (FBDs) and solving problems related to the laws of motion.

An object usually experiences four primary forces. First is the gravitational force (or weight) pulling it downward. Surfaces exert normal force, while frictional force works against motion. Then the applied or tension force starts any movement. These forces can either balance each other out or be unbalanced.