The strength of the gravitational field is given by:

where
G is the gravitational constant
M is the Earth's mass
r is the distance measured from the centre of the planet.
In our problem, we are located at 300 km above the surface. Since the Earth radius is R=6370 km, the distance from the Earth's center is:

And now we can use the previous equation to calculate the field strength at that altitude:

And we can see this value is a bit less than the gravitational strength at the surface, which is

.
Answer:
As ice melts into water, kinetic energy is being added to the particles. This causes them to be 'excited' and they break the bonds that hold them together as a solid, resulting in a change of state: solid -> liquid.
Explanation:
As we may know, the change in state of an object is due to the change in the average kinetic energy of the particles.
This average kinetic energy is proportional to the temperature of the particles.
This is because heat is a form of energy; by adding energy to ice - heat, you "excite" the water molecules, breaking the interactions in the lattice structure and forming weaker, looser hydrogen-bonding interactions.
This causes the ice to melt. This is demonstrated in the image below.
More generally, when you remove energy - the object cools down, the particles move a lot slower. So slow, that they individually attract other molecules more than before, and this results in a physical change that also changes the state.
Answer:
For cast iron we have

For copper

For Lead

For Zinc

Explanation:
As we know that final speed of the block is calculated by work energy theorem

now we have

now we have


For cast iron we have


For copper


For Lead


For Zinc


Answer:
Solenoid's inductance is 1.11 × 10^-8H
The average emf around the solenoid is 1.3 × 10^-5V
Explanation: Please see the attachments below
Answer:
A. Prism
Explanation:
In the experiment we are able to isolate different wavelengths by shining the light through a prism, which separates the different wavelengths through refraction.