Answer: Approximately 65% from what i have learnt.
Answer:
Explanation:
Given

angular velocity 
Combined moment of inertia of stool,student and bricks 
Now student pull off his hands so as to increase its speed to suppose
rev/s
After Pulling off hands so final moment of inertia is

Conserving angular momentum as no external torque is applied




Answer:
The Richter scale measures the largest wiggle (amplitude) on the recording, but other magnitude scales measure different parts of the earthquake. The USGS currently reports earthquake magnitudes using the Moment Magnitude scale, though many other magnitudes are calculated for research and comparison purposes.
Answer:
magnitude of gravitational force between the Earth and the Sun at B is greater than that at A
Explanation:
Formula of gravitational force:
F = GMm/r^2
(r is the distance between 2 objects)
We see that r(B) < r(A) since at B, the Earth is closer to the Sun than at A
According to the Formula, the smaller r is, the greater F is
So, F(B) > F(A)
Answer: C- ecosystem
An ecosystem is a biological community in which living beings interacts with their non-living environment. An ecosystem consists of abiotic ( non-living factors like water, sunlight, wind and soil) and biotic factors such as plants and animals. Ecosystem allows not only the interaction of abiotic and biotic factors but it favors the interaction between the living species. For example animals are dependent upon plants so as to derive their food. The coexistence of organisms favors the diversity of land forms on earth.
Communities of organisms coexist in organized, balanced ecosystems.