Answer:
Explanation:
a )
According to graph the object moves with constant velocity of 10 m /s during first 8 s and then its velocity changes to - 5 m /s from 8 th second upto 12 th second .
Initial displacement = 8 m
displacement during 8 s = velocity x time
= 8 x 10 = 80 m
total displacement = 88 m
b )
displacement during period from 8 th to 12 th s
= - 5 x 4 = - 20 m
total displacement after 12 s
= 88 - 20 = 68 m
c ) average speed = total distance covered during 12 s / total time
= (80 + 20) / 12
= 8.33 m /s
average velocity = total displacement during 12 s / total time
= 80 - 20 / 12
= 60 / 12
= 5 m /s .
Here the block has two work done on it
1. Work done by gravity
2. Work done by friction force
So here it start from height "h" and then again raise to height hA after compressing the spring
So work done by the gravity is given as
Now work done by the friction force is to be calculated by finding total path length because friction force is a non conservative force and its work depends on total path
Total work done on it
So answer will be
None of these
The ozone layer is beneficial because it protects us from the ultraviolet (UV) rays from the sun. Without it, survival would be difficult. It is harmful by containing all the pollution and chemicals . That damages our lungs and causes chest pain, coughing,etc.
Answer:
Option 3 and 6
Explanation:
If the particle is under the action of only one external force, both its kinetic energy and the velocity must vary.
When the particle is exerted by an external force, then this external force tends to accelerate the particle.
When the particle accelerates, its velocity must vary for that acceleration to occur.
When the velocity of the particle changes then its Kinetic energy must vary with the velocity of the particle.
Initial velocity (u) = 2 m/s
Acceleration (a) = 10 m/s^2
Time taken (t) = 4 s
Let the final velocity be v.
By using the equation,
v = u + at, we get
or, v = 2 + 10 × 4
or, v = 2 + 40
or, v = 42
The final velocity is 42 m/s.
