The branch of Physics which deals with the motion of objects while taking into consideration the cause of motion is
dynamics
kinematics
statics
none of these
$(a)$ Draw velocity-time graph for the following cases
$(i)$ When the object is at rest.
$(ii)$ When the object is thrown vertically upwards.
$(b)$ A motorcyclist riding motorcycle $A$ who is travelling at $36\, km h^{-1}$ applies the brakes and stops the motorcycle in $10\, s$. Another motorcyclist of motorcycle $B$ who is travelling at $18\, km h^{-1}$ applies the brakes and stops themotorcycle in $20\, s$. Plot speed-time graph for the two motorcycles. Which of the two motorcycles travelled farther before it come to a stop ?
Starting from rest a scooter acquires a velocity of $36\, km h^{-1}$ in $10 \,s$ and then brakes are applied it takes $20\, s$ to stop. Calculate acceleration and distance travelled.
Two stones are thrown vertically upwards simultaneously with their initial velocities $u _{1}$ and $u _{2}$ respectively. Prove that the heights reached by them would be in the ratio of $u_{1}^{2}: u_{2}^{2}$ (Assume upward acceleration is $-\,g$ and downward acceleration to be $+g$.
$(a)$ Differentiate between distance and displacement.
$(b)$ Under what conditions is the magnitude of average velocity of an object equal to its average speed ?
Ali while driving to school computes the average speed for his trip to be $20\, km h^{-1}$. On his return trip along the same route there is less traffic and the average speed is $30\, km h^{-1} .$ What is the average speed for Ali's trip ?