Search Colleges, Courses, Exams, Questions and Articles

Ask a query on 8879100846 Ask Login | Sign Up

 

 

› Ask & Answer › Question

A motor car moving at a speed of 72km/h can not come to a stop in less than 3.0 s while for a truck this time interval is 5.0 s. On a higway the car is behind the truck both moving at 72km/h. The truck gives a signal that it is going to stop at emergency. At what distance the car should be from the truck so that it does not bump onto (collide with) the truck. Human response time is 0.5s.

0 13 Views | Posted 4 months ago
Asked by Shiksha User

  • 1 Answer

  • P

    Answered by

    Payal Gupta | Contributor-Level 10

    4 months ago

    This is a long answer type question as classified in NCERT Exemplar

    speed of car and truck = 72km/h = 72 (5/18) =20m/s

    V= u+at

    0=20+a (5) so a=-4m/s2

    But retarted acceleration will be v=u+at

    0=20+a (3)

    So a= 20 3 t - 0.5 -20/3m/s2

    We also need to consider human response time = 0.5 s

    V=u-at (for retarded motion)

    V= 20- 20 3 t - 0.5 ….1

    Vt=20-4t ….2

    From 1 and 2

    20-=20-4t

    After solving we get t= 5/4s

    Distance travelled by truck in time t, S=ut+1/2at2

    = 20 × 5 4 + 1 2 - 4 × 5 4 2 = 21.875 m

    To avoid the bump onto the truck car must maintain distance = 23.125-21.875=1.250m

Similar Questions for you

Two trains 101 m and 99 m in length are running in opposite direction with velocities 54 km/h and 36 km/h. In what time they will completely cross each other?
A
alok kumar singh

Kindly go through the solution '

 

Distance travelled by a particle starting form rest and moving with an acceleration of 4/3ms-2 in the second is

 
A
alok kumar singh

Please find the solution below:

 

 

Match List – I with List – II :

List – I                                                                               List – II

(a) h (Planck’s constant)                                               (i) [ M L T − 1 ]  

(b) E (kinetic energy)                                                     (ii) [ M L 2 T − 1 ]        

(c) V (electric potential)                                                (iii) [ M L 2 T − 2 ]  

(d) P (linear momentum)                                             (iv) [ M L 2 I − 1 T − 3 ]  

Choose the correct answer from the options given below:
V
Vishal Baghel

[h] = ML2T-1

[E] = ML2T-2

[V] = ML2T-2C-1

[P] = MLT-1

 

A small toy starts moving from the position of rest under a constant acceleration. If it travels a distance of 10m in t s, the distance travelled by the toy in the next t s will be:
A
alok kumar singh

According to question, we can write

 10 = 1 2 a t 2 . . . . . . . . . . . . . . . ( 1 )     a n d                        

1 0 + x = 1 2 a ( 2 t ) 2 . . . . . . . . . . . . . . . . ( 2 )  

⇒ X = 1 2 A [ ( 2 t ) 2 − t 2 ] = 3 ( 1 2 a t 2 ) = 3 0 m  

 

A vehicle travels half the distance with speed  v and the remaining distance with speed 2 v . Its average speed is:
A
alok kumar singh

Average speed = 4 v 2 3 v

= 4 v 3

(d) Initial velocity  = - v j ˆ

Final velocity = v i ˆ

Change in velocity  = v i ˆ - ( - v j ˆ )

= v ( i ˆ + j ˆ ) Momentum gain is along i ˆ + j ˆ

⇒  Force experienced is along i ˆ + j ˆ

  ⇒ Force experienced is in North-East direction.

Get authentic answers from experts, students and alumni that you won't find anywhere else

Sign Up on Shiksha

On Shiksha, get access to

  • 65k Colleges
  • 1.2k Exams
  • 682k Reviews
  • 1800k Answers

Learn more about...

Share Your College Life Experience

Write a Review

Didn't find the answer you were looking for?

Search from Shiksha's 1 lakh+ Topics

or

Ask Current Students, Alumni & our Experts

Ask Now
Community GuidelinesUser Points System
QuestionsDiscussionsTags
×
×

This website uses Cookies and related technologies for the site to function correctly and securely, improve & personalise your browsing experience, analyse traffic, and support our marketing efforts and serve the Core Purpose. By continuing to browse the site, you agree to Privacy Policy and Cookie Policy.

Need guidance on career and education? Ask our experts

Characters 0/140

The Answer must contain atleast 20 characters.

Add more details

Characters 0/300

The Answer must contain atleast 20 characters.

Keep it short & simple. Type complete word. Avoid abusive language. Next

Your Question

Edit

Add relevant tags to get quick responses. Cancel Post