Answer:
This question can be answered by using conversation of energy.



Explanation:
Note that we take
because we are looking for the minimum initial speed for the penguin to reach the top of the second hill. Any other speed more than this will already be enough for him.
Answer:
There are 756.25 electrons present on each sphere.
Explanation:
Given that,
The force of repression between electrons, 
Let the distance between charges, d = 0.2 m
The electric force of repulsion between the electrons is given by :




Let n are the number of excess electrons present on each sphere. It can be calculated using quantization of charges. It is given by :
q = ne


n = 756.25 electrons
So, there are 756.25 electrons present on each sphere. Hence, this is the required solution.
Answer:
Part a)

Part B)

Part c)

Explanation:
Part a)
As we know that

so we will have





Part B)
Angular speed of the yo-yo

so we have


Part c)
Tangential acceleration is given as



Answer:
2.000.000.000
Explanation:
Apply the formula:
Work = Force . Displacement
W = 500.10 . 400.000 (the 10 come from gravity)
W = 5000 . 400.000
W = 2.000.000.000 Joules
I think it is that, can be wrong.
Answer:
129.6 seconds
Explanation:
Given that :
α = 0.0002°c-1
θ1 = 20°C
θ2 = 5°C
Time t = one day ; Converting to seconds ; number of seconds in a day ; (24 * 60 * 60) = 86400 seconds
Let dT= change in time
Using the relation :
dT = 0.5* α * dθ * t
dθ = (20 - 5) = 15°C
dT = 0.5 * 0.0002 * 15 * 86400
dT = 129.6 seconds