Out of the three speed$-$time graphs shown below
Identify the graph for the following cases.
$(i)$ A ball thrown vertically upwards and returning to the hand of the thrower ?
$(ii)$ A body decelerating to a constant speed and accelerating.
$(i)$ Graph $(a)$ shows that the speed of a body decreases with time becomes zero and then again starts increasing. This graph, therefore, represents the case of a ball thrown vertically upwards and then caught by the thrower. Initially, the ball is thrown with some speed. As the ball rises up its speed decreases at a constant rate, becomes and zero at maximum height. The ball then falls with a uniform acceleration till its speed becomes equal to speed of projection.
$(ii)$ Graph $(c)$ represents deceleration of the body to some constant speed, and then accelerating after sometime.
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 ?
There is an argument about uniform acceleration between $Mr$ $X$ and $Mr$ $Y.$ $Mr$ $X$ says "acceleration means that farther you go faster you go". $Mr$ $Y$ says "acceleration means that longer you go the faster you go". Whose statement is correct ?
How can you find the following ?
$(i)$ Velocity from a displacement$-$time graph.
$(ii)$ Acceleration from velocity$-$time graph.
$(iii)$ Displacement from velocity$-$time graph.
$(iv)$ Velocity from acceleration$-$time graph.
$(a)$ Differentiate between speed and velocity.
$(b)$ When is a body said to have uniform velocity ?
$(c)$ How can we describe the position of an object ? Illustrate with suitable example.
An electric train is moving with a velocity of $120\, km h^{-1} .$ How much distance will it corer in $30 \,s$ ?