Subject: Science
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 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 (d_{1}) = 10 m
distance (d_{2}) = 32 m
time (t_{1}) = 2 s
time (t_{2}) = 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.
For example, People in running vehicle is at rest with respect to the vehicle but at motion with respect to the road.
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.
Define uniform velocity.
If a moving body covers equal distances in equal intervals of time, then the body is said to have uniform velocity.
Describe the motion of the object in which its speed is constant but the velocity is changing
When a body is moving in a curved path with uniform speed, it’s speed remains same but the velocity is changing at each point of the curved path. This is because the direction of motions of the body is changing continuously.
Light travel 300000km/s. Is it velocity or speed?
Light travels 300000km/s is a velocity because light travels in a straight line in a fixed path.
A truck is moving at the rate of 72k/hr. How far does the truck move if it stops after 5 second?
Solution:
Initial velocity of a car = 72 k/hr
= (72 x 1000/60 x 60)
= 72000/300
= 20 m/s
Final velocity of truck = 0
Time taken = 5 sec
Distance =?
We know,
a = v – u / t
= 0 – 20/ 5
= -20/5
= -4 m/s²
Now, distance (s) = u x t + ½ at²
= 20 x 5 + ½ (-4) x 5²
= 100 - ½ x 4 x 25
= 100 - ½ x 50
= 100 – 50
= 50 m
An object is thrown vertically upwards with an initial velocity 20 m/s. Find the height if it reached the ground after 2 seconds.
Solution,
Initial velocity (u) = 20 m/s
Final velocity (v) = 0
Time taken (t) = 2 sec
Height (h) =?
Acceleration due to gravity = 10m/s²
We know,
v² = u² - 2gh
or, 0² = 20 – 2 x 10 x h
or, 0 = 400 – 20h
or, 20h = 400 – 0
or, h = 400/20
h = 20 m
Thus, the height after 2sec. is 2m.
Two jeeps A and B are moving in opposite direction to each other with a velocity of 70 km/hr and 20km/hr respectively. Calculate the relative velocity with reference to each other.
Jeep A relative to jeep B will be 50km/hr opposite to jeep B.
Jeep B relative to jeep A will be 50km/hr opposite to Jeep A.
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