 # Lakhmir Singh Solutions Class 9 Physics Solutions for Exercise in Chapter 1 - Motion

a) Define velocity. What is the SI unit of velocity?

b) What is the difference between speed and velocity?

c) Convert speed of 54 km/h into m/s.

a) Velocity is defined as the distance travelled by the body in unit time in a given direction. The SI unit of velocity is m/s.

b) The difference between speed and velocity is:

i) Speed is a scalar quantity while velocity is a vector quantity.

ii) Speed is always positive while velocity can be either positive or negative.

iii) Speed is defined as the distance travelled in unit time while velocity is the distance travelled in unit time in a particular direction.

c) Speed = 54 km/h = (54)(1000/3600) = 15 m/s

Video transcript
"hey guys how are you i hope you're good i am vineet your lido tutor welcoming you to little q a video i am excited to bring you this question on your screen define velocity what is the si unit of velocity then we are going to say see what is the difference between speed and velocity then we are going to convert speed of 15 kilometer per hour into meter per second now let us look at part a velocity is the distance covered by a moving object per unit time oh wait a minute this sounds like the definition of speed so what is the difference the difference is in a given direction right and the si unit is meter per second okay now let us look at the part b right and let us look at the differences between velocity and speed so here we go so we have speed and velocity speed is a scalar quantity velocity is a vector quantity and can be negative this is always positive right number two speed doesn't have direction velocity has direction so these are the differences now let us look at number three or c c is 54 kilometer per hour can also be written as 54 kilometer by one hour so this is equal to when we convert this into meter we get 54 000 because we multiply by thousand meters by three thousand six hundred seconds so simplifying this we get so six six are 36 6 90 3 2 30 to 1 15. we get 15 meter per second so that was easy isn't it guys right do leave a comment if you still have a doubt and do like the video and subscribe to our channel i'll see you in our next video until then bye guys keep learning keep flourishing"
Related Questions
Exercises

Lido

Courses

Teachers

Book a Demo with us

Syllabus

Maths
CBSE
Maths
ICSE
Science
CBSE

Science
ICSE
English
CBSE
English
ICSE
Coding

Terms & Policies

Selina Question Bank

Maths
Physics
Biology

Allied Question Bank

Chemistry
Connect with us on social media!