$A$ vehicle of $100\, kg$ is moving with a velocity of $5\, m/s$. To stop it in $\frac{1}{10}\, s$,the required force in the opposite direction is ........... $N$.

State and explain Newton's second law of motion. Write its important points.

$5\, kg$ દળ ધરાવતા એક પદાર્થ પર અચળ બળ $\overrightarrow F = {F_x}\hat i + {F_y}\hat j$ લાગે છે. $t = 0\, s$ સમયે તેનો વેગ $\overrightarrow v = (6\hat i - 2\hat j)\, m/s$ છે અને $t = 10\, s$ સમયે તેનો વેગ $\overrightarrow v = 6\hat j\, m/s$ છે. તો બળ $\overrightarrow F$ શોધો.

An object of mass $2 \, kg$ at rest at the origin starts moving under the action of a force $\vec{F} = (3t^2 \hat{i} + 4 \hat{j}) \, N$. The velocity of the object at $t = 2 \, s$ will be ............. $m/s$.

The driver of a three-wheeler moving with a speed of $36\; km/h$ sees a child standing in the middle of the road and brings his vehicle to rest in $4.0\; s$ just in time to save the child. What is the average retarding force (in $N$) on the vehicle? The mass of the three-wheeler is $400\; kg$ and the mass of the driver is $65\; kg$.

An object of mass $2 \, kg$ is placed at rest in a frame $S_1$ moving with velocity $10 \hat{i} + 5 \hat{j} \, m/s$ and having acceleration $5 \hat{i} + 10 \hat{j} \, m/s^2$. The object is also seen by an observer standing in a frame $S_2$ moving with velocity $5 \hat{i} + 10 \hat{j} \, m/s$. Calculate the net force acting on the object with respect to the $S_1$ frame.