Can the speed of a body be negative ?
The graph given below is the distance$-$time graph of an object.
$(i)$ Find the speed of the object during first four seconds of its journey.
$(ii)$ How long was it stationary ?
$(iii)$ Does it represent a real situation ? Justify your answer.
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.
The velocity$-$time graph of a car is given below. The car weighs $1000\, kg$.
$(i)$ What is the distance travelled by the car in the first $2$ seconds ?
$(ii)$ What is the braking force at the end of $5$ seconds to bring the car to a stop within one second ?
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 $+g$.