位置與運動

A girl walks along a straight road from a point $A$ to a point $B$ with an average speed $1$ m s$^{-1}$. She then returns from $B$ to $A$ along the same road with an average speed $2$ m s$^{-1}$. Find the average speed of the girl for the whole journey.

A racing car accelerates from rest to a speed of $100$ km h$^{-1}$ in $3.2$ s. Find the average acceleration of the car.

A car undergoes uniform deceleration along a straight road. Its velocity decreases from $30$ m s$^{-1}$ to $20$ m s$^{-1}$ after travelling a distance of $100$ m. How much further will the car travel before it comes to a rest ?

The velocity-time graph of a car travelling along a straight horizontal road is shown above. Which of the following graphs shows the variation of the acceleration $a$ of the car with the time $t$ ?

A student walks along a curve $ABC$, which is made up of two semi-circular parts $AB$ and $BC$ of radius $3$ m and $4$ m respectively. He takes $2$ s to walk from $A$ to $B$ and $5$ s from $B$ to $C$. Find the magnitude of the average velocity of the student from $A$ to $C$.

A particle is released from rest and falls vertically under gravity. If the distance travelled by the particle in the 1st second is $x$ and that travelled in the 2nd second is $y$, find the ratio $x : y$.

A man walks $40$ m towards the west. He then walks $40$ m towards the south and lastly walks $70$ m towards the east. Find the magnitude of the resultant displacement of the man.

An object moves with uniform acceleration along a straight line. Which of the following graphs correctly describe(s) the motion of the object ?

An object starts from rest and moves with uniform acceleration along a straight line. Which of the graphs below concerning the motion of the object is/are correct ? ($s$ = displacement, $v$ = velocity, $t$ = time)

The above diagram shows the variation of the velocity of an object with time. What is the distance travelled by the object in the first $3$ seconds ?