Answer:
4Al + 3Mno2 --> 2Al2o3 + 3Mn
Explanation:
Al = 1 x 4 = 4
Mn = 1 x 3 = 3
O = 2 x 3 = 6
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Al = 2 x 2 = 4
Mn = 1 x 3 = 3
O = 2 x 3 = 6
Answer:
Ultraviolet rays from sun are very harmful from skin and can cause sunburn and skin diseases especially ultraviolet B rays.<em> A sunscreen lotion act as a protection barrier on the skin that restrict the direct contact of UV rays with skin and filter the harmful rays to enter the skin. </em>
Radiotherapy is a medical therapy use to treat cancer. <em>Radiotherapy commonly uses x-rays and gamma rays because they are high-energy particles or waves that kills or destroys the cancer cells.</em>
Answer:
240000 Joules
Explanation:
Applying,
The work that must be done by the frictional force of the brake to stop the car must be equal to the kinetic energy of the car.
W = mv²/2.................. Equation 1
Where W = work done by the frictional force of the brake, m = mass of the car, v = velocity of the car.
From the question,
Given: m = 1200 kg, v = 20 m/s
Substitute these values into equation 1
W = (1200×20²)/2
W = 240000 Joules
Ω₀ = the initial angular velocity (from rest)
t = 0.9 s, time for a revolution
θ = 2π rad, the angular distance traveled
Let
α = the angular acceleration
ω = the final angular velocity
The angular rotation obeys the equation
(1/2)*(α rad/s²)*(0.9 s)² = (2π rad)
α = 15.514 rad/s²
The final angular velocity is
ω = (15.514 rad/s²)*(0.9 s) = 13.963 rad/s
If the thrower's arm is r meters long, the tangential velocity of release will be
v = 13.963r m/s
Answer: 13.963 rad/s
If the kinetic energy of each ball is equal to that of the other,
then
(1/2) (mass of ppb) (speed of ppb)² = (1/2) (mass of gb) (speed of gb)²
Multiply each side by 2:
(mass of ppb) (speed of ppb)² = (mass of gb) (speed of gb)²
Divide each side by (mass of gb) and by (speed of ppb)² :
(mass of ppb)/(mass of gb) = (speed of gb)²/(speed of ppb)²
Take square root of each side:
√ (ratio of their masses) = ( 1 / ratio of their speeds)²
By trying to do this perfectly rigorously and elegantly, I'm also
using up a lot of space and guaranteeing that nobody will be
able to follow what I have written. Let's just come in from the
cold, and say it the clear, easy way:
If their kinetic energies are equal, then the product of each
mass and its speed² must be the same number.
If one ball has less mass than the other one, then the speed²
of the lighter one must be greater than the speed² of the heavier
one, in order to keep the products equal.
The pingpong ball is moving faster than the golf ball.
The directions of their motions are irrelevant.
