Velocity

The velocity of the body is the distance travelled by it in unit time to a certain direction. If a moving body covers the equal distance in equal interval of time , then the body is said to have uniform velocity. If a moving body covers the different distance in unit time then the body is said to have variable velocity. This note provides information about velocity, definition, example and help for numerical problem.

Summary

The velocity of the body is the distance travelled by it in unit time to a certain direction. If a moving body covers the equal distance in equal interval of time , then the body is said to have uniform velocity. If a moving body covers the different distance in unit time then the body is said to have variable velocity. This note provides information about velocity, definition, example and help for numerical problem.

Things to Remember

  • The velocity of the body is the distance travelled by it in unit time to a certain direction.

  • Uniform velocity: If a moving body cover the equal distance in equal interval of time , then the body is said to have uniform velocity.

  • Variable velocity:If a moving body covers  the different distance in unit time then the body is said to have variable velocity.

  • Relative velocity: The laws of physics which apply when you are at rest on the earth also apply when you are in any reference frame which is moving at a constant velocity with respect to the earth.

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Subjective Questions

Q1:

Write a letter to your sister regarding her exam results.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Daksinamurti Marg,</p> <p>Mitrapark, Kathmandu</p> <p>Nepal.</p> <p>May 3, 2006</p> <p>Dear sister,</p> <p>Thanks to Harka uncle who told me about your failure in exam and frustration caused by it. After hearing the news, I couldn&rsquo;t stop myself without writing a few of words regarding it.</p> <p>Sister, life is said &ldquo;Full of struggle&rdquo;. Another side of life is failure too. It is said, &ldquo;No pain, no gain&rdquo;. Being a wise, bold and courageous girl, you can easily understand what I mean. You might have gone through several pages of history where you might have found many ups and downs faced even by a successful man. Founder of Modern Nepal; PN Shah who tasted many failures during his unification and in course to annex Nuwakot. But he never lost his hope and learnt the lesson from his failure. He regained his new spirit and jumped into the battle with full preparation. As a result, he got success and unified tiny principalities into a greater Nepal. So, being a wise and lovely girl, it is not good to show your frustration. Please wake up and regain your energy to fight back against your failure. I think, your failure can be a ladder to gain your ultimate goal. Be confident and sure, you&rsquo;ll never look back if you learn lesson from your mistakes.</p> <p>Finally, convey my best regards to mom and dad and love to brother Sujel. Think twice; recollect your energy, be bold, to face new challenges and dilute all the tiny problems. Your bright future is eagerly waiting to give you back your smile and happiness.</p> <p>I look forward to hearing soon.</p> <p>Your Loving Sister,</p> <p>Apphia Shrestha.</p>

Q2:

Write a letter to your father regarding your school and aim of life.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Mitrapark, Kathmandu</p> <p>Nepal</p> <p>10<sup>th</sup> May, 2006</p> <p>Dear Father,</p> <p>As you asked me to write something about my school and aim of life, I&rsquo;m going to write something about it. The school is very good and my aim of life is to be an English teacher.</p> <p>When I joined the school, at that time I got bad impression about it. The school didn&rsquo;t have big building and play ground. I was very sad and disappointed. From the first day only what I remembered, the classes were memorable. I found all my colleagues were very helpful and discipline. Teachers were equally good. All the teachers were got trained, laborious, smart and helpful. The teachers of the school were really very good. I, who never passed in Maths, now I&rsquo;m among good students, the credit goes to Dhami sir. Science teacher makes the subject matter easy to everyone. He always encourages me to do well in science. But I&rsquo;m much impressed by my English teacher, Dev sir. His way of teaching is very impressive. He doesn&rsquo;t only teach but tells the students how to write, digest and express in English. Because of his effort, I&rsquo;m completely changed. I&rsquo;m not that student who was roaming and measuring Kathmandu&rsquo;s street. I&rsquo;ve not touched my lovely guitar to book.</p> <p>I&rsquo;m quite impressed by the simplicity of my English teacher. His simplicity, smartness and even his problems cannot be read in his face. He always smiles and thinks betterment of the students. Such a teacher can be apple of one&rsquo;s eyes and dearer to everyone.</p> <p>Finally, I&rsquo;d like to say my school is far better than so called good schools of Kathmandu. Though my friends have aim like to be doctor and engineer. But I&rsquo;d like to be an English teacher like Dev Sir.</p> <p>Please convey my best regards to mom and love to brother Nishan. We&rsquo;ll have chat when we&rsquo;ll be together during vacation.</p> <p>I look forward to hearing you soon.</p> <p>Yours lovingly,</p> <p>Meena Shrestha.</p> <p></p>

Q3:

Write a letter describing your village.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Dakshinamurti Marg</p> <p>Mitrapark, Kathmandu</p> <p>2<sup>nd</sup> Chaitra, 2063</p> <p>Dear Sukmit,</p> <p>I was overwhelmed when I got through your previous letter and came to know a lot about your previous letter and came to know a lot about your village. I also would like to describe you about my village.</p> <p>My village is Lahila which is located at Sankhu in Kathmandu District. It is a dormitory town with Newar settlement. It is the ancient place where there is mythology of Swasthani, green forest, hills, Sali Nadi. There are many temples like Indrayani, Bajra Yogini and Gumbas. Nearly, ten thousand people live in this place. Due to conscious people and their unity, this area has developed a lot. There are facilities of electricity, transport, communication etc. there are many schools and health posts too. But still people are conservative and they believe in orthodox practices. Nowadays, people are being conscious due to education and awareness programmes. Thus, I love my village.</p> <p>Finally, convey my best regards to your mom and dad and love to sister Barsha.</p> <p>I look forward to hearing you soon.</p> <p>Yours lovingly,</p> <p>Meena Shrestha.</p>

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Velocity

Velocity

The velocity of the body is the distance travelled by it in unit time in a certain direction. It is the rate of change of the distance of an object in a particular direction.If a body travels a distance of S-meter in t seconds in a given direction, then,

Velocity = Distance travelled in a given direction/ time taken=S/T (meters per second)

Average Velocity

Average velocity can be defined as the distance travelled divided by the time elapsed.

average velocity= displacement/time taken

here, v= velocity

s= displacement

t= time taken

Example: If a car travels 10 meters in 2 seconds and travels 32 meters in another 5 seconds then calculate its' average velocity.

Solution here,

distance (d1) = 10 m

distance (d2) = 32 m

time (t1) = 2 s

time (t2) = 5 s

= 42/7 = 6 m/s.

Therefore, the average velocity is m/s.

If initial velocity of an object is u and final velocity of an object is v then,

Example: If a tempo travels with a speed of 5 m/s. How far will it reach in one more hour?

Here,

Speed (v) = 5 m/s

Time (t) = 1 hour

= 60 x 60 sec

= 3600 sec

Distance(s) =?

We have,

Or, s = v x t

= 5 m/s x 3600 s

= 18000 m

= 18 km

Thus, the tempo travels 18 km in one hour.

The unit of velocity is the same as that of speed, namely, meter per second. Velocity has magnitude as well as direction, therefore, velocity is a vector quantity.The velocity of a car shows its definite direction.

  • Uniform velocity: In uniform velocity, a moving body covers the equal distance in equal interval of time, then the body is said to have uniform velocity.
  • Variable velocity: If a moving body covers the different distance in unit time then the body is said to have variable velocity.
  • Relative velocity: The laws of physics which apply when you are at rest on the earth also apply when you are in any reference frame which is moving at a constant velocity with respect to the earth. The motion may have the different appearance as viewed from a different reference frame, but this can be explained by relative point.

For example, People in running vehicle is at rest with respect to the vehicle but at motion with respect to the road.

Lesson

Velocity and Acceleration

Subject

Science

Grade

Grade 8

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