Hello
1) The work W is calculated as the product between the force F applied to the cart and the distance d covered by the cart:
2) The force is the product of the mass m of the cart and its acceleration a:
If we use this into the formula of the work, we get
3) The cart is moving by accelerated motion. For this kind of motion, we have the following relationship:
where
and
are the final and the initial velocity of the cart.
Re-arranging we have
4) Therefore, we can subsitute
into the original formula of the work, and we get
1) The half-life is the time required for a substance to reduce to half its initial value. In formulas:
(1)
where
m(t) is the amount of substance left at time t
m0 is the initial mass
is the half-life
In this problem, the half-life of the substance is 20 years:
therefore, the fraction of sample left after t=40 years will be
So, only 1/4 of the original sample will be left, which corresponds to 25%.
2) We can use again formula (1), by re-arranging it:
If we use m(t)=10 g (mass of uranium left at time t), and
(the time is equal to 4 half lifes), we get
So, the initial sample of uranium was 160 g.
Answer:
A. velocity and wavelength
Explanation:
When a wave travels from one medium to another it undergoes refraction which results to the change in direction.
Refraction of a wave is one of the property of waves that occurs when a wave changes direction when it passes from one medium to another. This occurs as a result of bending of the wave which occurs since the mediums involved are of different density and refractive index.
Apart from the change in direction, refraction is accompanied by the change in wavelength of a wave and thus a change in speed.
Answer:
(a) 18.87 V
(b) 23.81 V
(c) 20.75%
Explanation:
The answers are given in the pictures. I have attached the pictures because circuits were needed to be drawn which are easier to understand when done on page. The page are numbered on top left corner.
Answer:
They're going to increase the total resistance as
Explanation:
If the resistors are in parallel, the potential difference is the same for each resistor. But the total current is the sum of the currents that pass through each of the resistors. Then
where
but
for
so
where