Answer:
Explanation:
Before it hits the ground:
The initial potential energy = the final potential energy + the kinetic energy
mgH = mgh + 1/2 mv²
gH = gh + 1/2 v²
v = √(2g (H - h))
v = √(2 * 9.81 m/s² * (0.42 m - 0.21 m))
v ≈ 2.0 m/s
When it hits the ground:
Initial potential energy = final kinetic energy
mgH = 1/2 mv²
v = √(2gH)
v = √(2 * 9.81 m/s² * 0.42 m)
v ≈ 2.9 m/s
Using a kinematic equation to check our answer:
v² = v₀² + 2a(x - x₀)
v² = (0 m/s)² + 2(9.8 m/s²)(0.42 m)
v ≈ 2.9 m/s
Answer: Yes, the dog's head will burn
Explanation:Solar winds are strongly destructive magnetically charged high energy winds. Satellite communication on earth and the occasional geomagnetic storm near the poles are the major disruptive effects caused by solar winds on earth.
Since solar winds are streams of charged particles released from the upperparts of the Sun, called the "corona". This plasma mainly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. Instilled within the solar-wind plasma is the interplanetary magnetic field.
If the dog holds it's breath the heat wave would burn it's head but not outrightly because the breath has ceased for some seconds and it can't absorb the much heat of the solar wind into it's nostrils. The effect of holding its breath would still be disastrous but not as the first case.
By Bernoulli Theorem, We know, that for any two points in the pipe, total energy would be same.
Pressure Energy + K.E. of 1st pipe = Pressure Energy + K.E. of 2nd pipe
[ No need to consider Potential energy as height isn't mentioned]
P₁ + mv₁²/2 = P₂ + mv₂²/2
So, we know, P + mv²/2 = constant
As value of kinetic energy is larger in larger in 2 in. pipe [ 'cause area is indirectly proportional to velocity ], Value of pressure energy would be smaller in it. So, pressure energy will be higher in the pipe of 3 in.
In short, option A would be your correct answer.
Hope this helps!
Answer:
5 x 10⁻⁷N
Explanation:
Given parameters:
Mass of object 1 = 100kg
Mass of object 2 = 300kg
Distance = 2m
Unknown:
Force of gravitational attraction between the objects = ?
Solution:
Newton's law of universal gravitation states that the gravitational force between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
From Newton's law of universal gravitation we derive an expression:
Fg = 
G is the universal gravitation constant = 6.67 x 10⁻¹¹
m is the mass
r is the distance between the bodies
Now insert the parameters and solve;
Fg = 6.67 x 10⁻¹¹ x 
= 5 x 10⁻⁷N
Answer:
D)378kJ
Explanation:
Applying,
E = F×d................ Equation 1
Where E = Energy expanded by the car, F = Wind resistance, d = distance
From the question,
F = 0.42v²............ Equation 2
Susbtitute equation 2 into equation 1
E = 0.42v²d.............. Equation 3
Given: v = 30 m/s, d = 1 km = 1000 m
Substitute these values into equation 3
E = 0.42(30²)(1000)
E = 378000
E = 378 kJ
Hence the right option is D)378kJ
