Answer:
Part a)

Part b)



Part c)



Explanation:
Part a)
As we know that charge density is the ratio of total charge and total volume
So here the volume of the charge ball is given as



now the charge density of the ball is given as

Part b)
Now the charge enclosed by the surface is given as

at radius of 5 cm


at radius of 10 cm


at radius of 20 cm

Part c)
As we know that electric field is given as

so we have electric field at r = 5 cm


electric field at r = 10 cm


electric field at r = 20 cm


Solution :-
Given :
Distance 1 = 30 km
Distance 2 = 70 km
We know that speed = distance/time
and, Average speed = total distance/total time taken
When the train acquired a speed of 30 km/hr, the time taken = 30/30 = 1 hour
Average speed = 9distance 1 + distance 2)/(time 1 + time 2)
AS time 2 or t2 is time taken for the second part of the journey of 70 km
⇒ 40 = 100/(1 + t2)
⇒ 40 + 40t2 = 100
⇒ 40t2 = 100 - 40
⇒ 40t2 = 60
⇒ t2 = 60/40
⇒ t2 = 1.5
So, t2 or time taken to travel the second part of the journey is 1.5 hours.
Speed of the second part of the journey = distance 2/time 2
⇒ 70/1.5
⇒ 46.666 km/hr or 46.7 km/hr.
Hence the answer is = 46.666 km/hr or 46.7 km/hr.
Hope it helped u if yes mark me BRAINLIEST!
Tysm!
:)
Answer
2) 1.5×10-2 m
Explanation
The potential difference is related to the electric field by:
(1)
where
is the potential difference
E is the electric field
d is the distance
We want to know the distance the detectors have to be placed in order to achieve an electric field of

when connected to a battery with potential difference

Solving the equation (1) for d, we find

Answer:
a) The flea's speed when it leaves the ground is 
b) The flea move
upward while it is pushing off
Explanation:
Hi
<u>Knwons</u>
Mass
, Work
and Force 
a) Here we are going to use
, so 
a) Here we are going to use
, so
or
approx.
Answer:
this the way that hydraulic pump works:
The system of hydraulic jack lifts the heavy objects by transferring the oil from one chamber to another.
Through the suction valves into the two cylinders which creates pressure distributing the fluid equally to the points causing the objects to lift up.
hope these points helped u
any confusion then comment it