Explanation:
Q1) What is the speed of the tip of the minute hand of a clock where the hand is of length 7cm?
Ans1) speed, v=st=2πrT=2×227×7×10-260×60=119×10-4=1.22×10-4m/s
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<em><u>Hope it helps</u></em></h2>
Answer:
a) The current density ,J = 2.05×10^-5
b) The drift velocity Vd= 1.51×10^-15
Explanation:
The equation for the current density and drift velocity is given by:
J = i/A = (ne)×Vd
Where i= current
A = Are
Vd = drift velocity
e = charge ,q= 1.602 ×10^-19C
n = volume
Given: i = 5.8×10^-10A
Raduis,r = 3mm= 3.0×10^-3m
n = 8.49×10^28m^3
a) Current density, J =( 5.8×10^-10)/[3.142(3.0×10^-3)^2]
J = (5.8×10^-10) /(2.83×10^-5)
J = 2.05 ×10^-5
b) Drift velocity, Vd = J/ (ne)
Vd = (2.05×10^-5)/ (8.49×10^28)(1.602×10^-19)
Vd = (2.05×10^-5)/(1.36 ×10^10)
Vd = 1.51× 10^-5
A) Calling F the intensity of the horizontal force and d the displacement of the block across the floor, the work done by the horizontal force is equal to

b) The work done by the frictional force against the motion of the block is equal to:


Part of these 105.1 Joules of work becomes increase of thermal energy of the block (

), and part of it becomes increase of thermal energy of the floor (

). We already know the increase in thermal energy of the block (38.2 J), so we can find the increase in thermal energy of the floor:

c) The net work done on the block is the work done by the horizontal force F minus the work done by the frictional force (the frictional force acts against the motion, so we must take it with a negative sign):

For the work-energy theorem, the work done on the block is equal to its increase of kinetic energy:

So, we have
T he role of oxygen in air supply is to keep all the ling beings live and healthy.
<h3>What is Oxygen?</h3>
Oxygen is the most important gas required for the living of human beings, animals, birds and the whole ecosystem.
Oxygen is fundamental for breath on the grounds that the body utilizes it to 'consume' food atoms. Creatures take in oxygen while breathing in and radiate carbon dioxide while breathing out. Oxygen makes up practically 21% of the all out gases in air, with the majority of the excess gas being physiologically latent nitrogen.
Oxygen assumes a basic part in breath, the energy-delivering science that drives the digestion systems of most living things. We people, alongside numerous different animals, need oxygen in the air we inhale to remain alive. Oxygen is created during photosynthesis by plants and many sorts of organisms.
Thus, the air supply needs oxygen on the majority.
Learn more about oxygen.
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