Time, Speed and Distance Questions

Multiple choice statistics moving averages moving average and variation simple moving average uses of average in day-to-day life introduction to time series introduction to time series and forecasting

Choose the correct answer from the alternatives given.
A man covers a distance of $160$ km at $64 km/hr$ and next $160$ km at $80 km/hr$. What is his average speed for his whole journey of $320$ km?

  1. $73.00km/h$
  2. $71.11km/h$
  3. $70.50km/h$
  4. $72.25km/h$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed is total distance divided by total time. Total distance is 160 + 160 = 320 km. Time 1 = 160/64 = 2.5 hours. Time 2 = 160/80 = 2 hours. Total time = 4.5 hours. Average speed = 320 / 4.5 = 71.11 km/h.

Multiple choice vedic methods of multiplication history of mathematics maths

Two trains starts from stations $A$ and $B$ and travel towards each other at speed of $50\ km/hr$ and $60\ km/hr$ respectively. At the time of their meeting, the second train has travelled $120\ km$ more than the first. The distance between $A$ and $B$ is

  1. $990\ km$
  2. $1200\ km$
  3. $1320\ km$
  4. $1440\ km$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Speed of train $A = 50\ kmph$
Speed of train $B = 60\ kmph$
Since, time is constant
$Speed \propto$ Distance covered
$\dfrac {S _{A}}{S _{B}} = \dfrac {D _{A}}{D _{B}}$
$\dfrac {50}{60} = \dfrac {D _{A}}{D _{B}}\Rightarrow \dfrac {5}{6} = \dfrac {D _{A}}{D _{B}}$
Given that train $B$ has travelled $120\ km$ extra.
$6x - 5x = 120$
$x = 120$
The distance between $A$ and $B = 6x + 5x = 11x$
$= 11\times 120 = 1320$
Alternate Method:
Let train $A$ start form station $A$ and $B$ from station $B$.
Let the trains $A$ and $B$ meet after/ hours.
$\therefore$ Distance covered by train $A$ in $t$ hours $= 50t$
Distance covered by train $B$ in $t$ hours $= 60t\ km$.
According to the question,
$60t - 50t = 120$
$\Rightarrow t = \dfrac {120}{10} = 12\ hours$.
$\therefore$ Distance $AB = 50\times 12 + 60 \times 12$
$= 600 + 720 = 1320\ km$.

Multiple choice conversion of time time conversion time measurement of time maths

A boat travels upstream from $B$ to $A$ and down stream from $A$ to $B$ in $3$ hours. If the speed of the boat in still water is $9\ km/hr$ and the speed of the current is $3\ km/ hr$, then the distance (in km) between $A$ and $B$ is

  1. $12$
  2. $8$
  3. $6$
  4. $4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let the distance between $A$ and $B$ be $x$ km.
Upstream speed $= 9 - 2 = 6\ kmph$
Downstream speed $= 9 + 3 = 12\ kmph$
$\dfrac {x}{6} + \dfrac {x}{12} = 3\Rightarrow \dfrac {2x + x}{12} = 3\Rightarrow 3x = 36 \Rightarrow x = 12\ km$.

Multiple choice maths compound measures and motion kinetic graphs time - calcuation of distance travel graphs

Fighter planes  $X$  and  $Y$  are moving towards a target $ 'O'$ along two perpendicular paths, with equal speeds.  $X$  starts from a point at a distance of  $19\mathrm { km }$  from  $^ { \prime } O ^ { \prime }$  and  $Y$  starts from a point at a distance of   $12\mathrm { km }$  from  $ \mathrm '{ O } '.$  After  $1$  minute, it was found that they were  $13\mathrm { km }$  away from each other. What is the speed at which they are travelling. given that they start simultaneously?

  1. $35 \mathrm { km } / \mathrm { min }$
  2. $28 \mathrm { km } / \mathrm { min }$
  3. $7 \mathrm { km } / \mathrm { min }$
  4. $21 \mathrm { km } / \mathrm { min }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice maths compound measures and motion kinetic graphs time - calcuation of distance travel graphs

A car travels 120 km from A to B at 30 km per hour but returns the same distance at 40 km per hour. The average speed for the round trip is closest to: 

  1. 33 km/hr

  2. 34 km/hr

  3. 35 km/hr

  4. 36 km /hr

  5. 37 km/hr

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If a car travels a distance d at rate $r _1$  and returns the same distance at rate $r _2$ , then 
Average speed = $\dfrac{total distance}{total time} = \dfrac{2d}{d/r _1+ d/r _2}= \dfrac{2r _1r _2}{r _1+r _2}$; 
$\therefore  x = \dfrac{2.30.40}{70} = \dfrac{240}{7} ~ 34 km/hr$.

Multiple choice maths compound measures and motion kinetic graphs time - calcuation of distance travel graphs

Mohit travelled $225$ km in $\displaystyle 4\frac {1}{2}$  hours. Raj travelled the same distance at an average speed that was $10$ km per hour faster than Mohit's average speed. What was the number of hours it took Raj to travel $225$ km ?

  1. $\displaystyle 2\frac {1}{4}$
  2. $\displaystyle 3\frac {1}{4}$
  3. $\displaystyle 3\frac {3}{4}$
  4. $\displaystyle 4\frac {2}{5}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the formula, $Speed=\frac { Distance }{ time } $
Mohit speed=
${ S } _{ m }=\frac { 225 }{ 4.5 } =50km/h$
${ S } _{ r }=50+10=60km/h$
Distance=225km
$Time=\frac { Distance }{ Speed } =\frac { 225 }{ 60 } =3\frac { 3 }{ 4 } hr$
Answer (C) $3\frac { 3 }{ 4 } hr$

Multiple choice maths compound measures and motion kinetic graphs time - calcuation of distance travel graphs

Two trains from two places start running in the opposite direction and reach the destination at the midpoint after  $3\dfrac{1}{3}$ hours and $4\dfrac{4}{5}$  hours. If the speed of the first train is $80$ km/hr, then the speed of the 2nd train (in km/hr) is

  1. $64\dfrac{2}{3}$
  2. $66\dfrac{2}{3}$
  3. $55\dfrac{5}{9}$
  4. $75$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$\text{Let speed of second train is x km/hr}$

$\text{if both train reaches the destination at the mid point then,}$

$\text{distance left to be covered by A = distance covered by B }.......(i)$
and
$\text{Distance = speed  x time taken}$

from (i)
$x\times\dfrac{24}{5}= 80 \times \dfrac{10}{3}$
$x=55\dfrac{5}{9}$

option c is correct


Multiple choice maths trigonometry trigonometric ratios of acute angles compound angles, multiple angles, sub multiple angles and transformation formulae trigonometric identities

A boat takes $19$ hours for travelling downstream from point $A$ to point $B$ and coming back to a point $C$ midway between $A$ and $B$. If the velocity of the stream is $4$ $kmph$ and the speed of the boat in still water is $14 \mathrm { kmph}, $ what is the distance between $A$ and $B$?

  1. $160km$
  2. $180km$
  3. $200km$
  4. $220km$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation


Speed in downstream =  $(14 + 4) km/hr = 18 km/hr ;$

Speed in upstream =  $(14 – 4) km/hr = 10 km/hr. $

Let the distance between A and B be $x$ km. Then,

$\frac{x}{18} + \frac{x}{2}\times\frac{1}{10}$ = 19 

$\Rightarrow \frac{x}{18} + \frac{x}{20}$ = 19 

$\Rightarrow$ $x = 180 km.$

Multiple choice physics study of sound determination of speed of sound by echo problems on sound sound needs a medium

A boy clapped his hands near a cliff and heard the echo after 4s. What is the distance of the cliff from the person if the speed of the sound, v is taken as 346 ms$^{-1}$?

  1. 2 m

  2. 1384 m

  3. 692 m

  4. 2768 m

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given, Speed of sound, $v = 346 ms^{-1}$ Time taken for hearing the echo, $t = 4 s$
Distance travelled by the sound $ = v \times t = 346 m/s \times 4 s = 1384 m$
In 4 s sound has to travel twice the distance between the cliff and the person.
Hence, the distance between the cliff and the person $= 1384 m/2 = 692 m$

Multiple choice physics propagation of sound waves longitudinal vs transverse wave sound and light comparison of speed of sound with speed of light

A worker lives at a distance of 1.32 km from the factory. If the speed of sound in air is 330 m$s^{-1}$, how long will the sound of factory siren take to reach the worker?

  1. 1 s

  2. 2 s

  3. 3 s

  4. 4 s

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given,


Distance $=1.32\,km=1320\,m$

Speed of sound in air $=330\,m/s$

We have,

$Time=\frac{Distance}{Speed}$

$Time=\frac{1320}{330}=4\,s$

Thus it would take $4\,s$ for the sound of the factory siren to reach the 
worker.

Multiple choice applications of quadratic equations solving (simple) problems word problems based on quadratic equations quadratic equation maths

A man walks a distance of 48 km in a given time. If he walks 2 km/hr faster, he will perform the journey 4 his before. His normal rate of walking is _______.

  1. 3 km/hr

  2. 4 km/hr

    • 6 km/hr or 4 km/hr
  3. 5 km/hr

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let us assume that the man walks at a speed of $x$ $kmph$

Then the time taken by the man to complete the journey is $t=\frac{48}{x}$  ($\because time=\frac {distance}{speed}$)
Now in the second case, $t'=t-3$ and $x'=x+2$.
Then, 
$t-4=\frac{48}{x+2}$
$\Rightarrow$ $t-\frac{48}{x+2}=4$
$\Rightarrow$ $\frac{48}{x}-\frac{48}{x+2}=4$
$\Rightarrow$ $\frac{96}{x(x+2)}=4$
$\Rightarrow$ $x^{2}+2x=24$
$\Rightarrow$ $x^{2}+2x-24=0$
$\Rightarrow$ $x^{2}-4x+6x-24=0$
$\Rightarrow$ $(x-4)(x+6)=0$
Speed cannot be a negative value and hence $x=4kmph$
$\therefore$ Option B is correct.

Multiple choice physics motion and measurement of distances motion around us motion and rest moving things around us

A boy running at an average speed of $4 km hr^{-1}$ reaches school from his home in $\frac{1}{2}hr$. The distance of the school from his home is

  1. $2 km$
  2. $8 km$
  3. $4 km$
  4. $6 km$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given:$v =4\frac{Km}{h}$
           

     $t =\dfrac{1}{2}$hour
   as $v=\dfrac{Distance}{t}$
        $Distance=4\times\dfrac{1}{2}$
        $Distance=2Km$