When particles in a substance slow down, we can infer that the object is getting colder. Why we can infer this:
1. Kinetic energy, is energy due to motion, therefore if there is no motion, there is no kinetic energy.
2. The colder an object get, the closer it becomes to having it's particles stopping completely, eventually at the absolute zero.
3. As kinetic energy increases, particles move faster. Kinetic energy usually increases when an object gets warmer. As kinetic energy decreases, particles move slower. Kinetic energy usually decreases when an object gets colder.
So, with this information, we now how and why the kinetic energy slows down.
The acceleration of the object which moves from an initial step to a full halt given the distance traveled can be calculated through the equation,
d = v² / 2a
where d is distance, v is the velocity, and a is acceleration
Substituting the known values,
180 = (22.2 m/s)² / 2(a)
The value of a is equal to 1.369 m/s²
The force needed for the object to be stopped is equal to the product of the mass and the acceleration.
F = (1300 kg)(1.369 m/s²)
F = 1779.7 N
1) See attached figure
The relationship between charge and current is:
where
i is the current
Q is the charge
t is the time
Therefore, the current is the rate of change of the charge passing through a given point over time.
This means that for a graph of charge over time, the current is just equal to the slope of the graph.
For the graph in this problem:
- Between t = 0 and t = 2 s, the slope is
therefore the current is
i = 25 A
- Between t = 2 s and t = 6 s, the slope is
therefore the current is
i = -25 A
- Between t = 6 s and t = 8 s, the slope is
therefore the current is
i = 25 A
The figure attached show these values plotted on a graph.
2)
The previous equation can be rewritten as
This equation is valid if the current is constant: if the current is not constant, then the total charge is simply equal to the area under a current vs time graph.
Here we have the current vs time graph, so we gave to find the area under it.
The area of the first triangle is:
While the area of the second square is
So, the total area (and the total charge) is
Answer:
Same as before.
Explanation:
we can use momentum conservation to solve the problem.
Let mass of child be m and of the sled be M. Also let both have initial velocity u.
since, child fells off on the sled it will still have same velocity of ''u''.
By momentum conservation we have,
(M + m) x u = m x u + M x v
⇒ Mu=Mv
⇒ u=v
Hence, velocity of the sled remains the same.
Answer:
1.2×10⁶ Hz
Explanation:
Applying,
v = λf............. Equation 1
Where v = speed of wave, λ = wavelength, f = frequency.
make f the subject of the equation
f = v/λ............... Equation 2
From the question,
Given: v = 3.0×10⁸ m/s, λ = 2.5×10² m
Substitute these values into equation 2
f = 3.0×10⁸/2.5×10²
f = 1.2×10⁶ Hz