Define and measure the speed
choose this
heliocentric theory = Ptolomeu
radioactivity = Becquerel
reflecting telescope - Newton (not sure)
Answer:
Explanation:
Given the wave function
y(x,t) = 0.340 sin (15πt − 4πx + π/4)
Generally a wave function is of the form
y(x, t) = A•Sin(wt - kx + θ)
Where
A is amplitude
w is angular frequency
θ is the phase angle
k is the wave number.
Then, comparing this with given wave function
k = 4π, w = 15π and θ = π/4
Speed and direction?
The speed of a wave function can be determined using wave equation
v = fλ
w = 2πf
Then, f = w/2π = 15π/2π = 7.5Hz
Also k = 2π/λ
Then, λ = 2π/k = 2π/4π = 0.5 m
Then,
v = fλ = 7.5 × 0.5
v = 3.75m/s
Direction
Since the time and distance coefficient have opposite sign, for an increasing time interval, the translation will have to increase in the positive direction to nullify the change and maintain the phase. Hence, the wave is traveling in the positive x direction
Answer:
the apparent weight of the astronaut is 81.032 N { towards moon }
Explanation:
Given that;
Mass of astronaut m = 80 kg
Distance of spaceship from the Earth's moon r = 2200 km = 2200 × 10³ m
Acceleration due to gravity of the moon = GM/r²
where M is mass of the moon( 7.34767309 × 10²² kg )
gravitational constant G = 6.67 × 10⁻¹¹
So,
Acceleration due to gravity of the moon g is;
g = [ (6.67 × 10⁻¹¹) × (7.35 × 10²²) ] / (2200 × 10³)²
g = 4.90245 × 10¹² / 4.84 × 10¹²
g = 1.0129 m/s²
now, we take the positive direction towards the moon if the spacecraft is moving with constant velocity, a = 0
The apparent weight is measured by the normal force FN
so,
∑F = ma
-FN + mg = ma
-FN + mg = 0
FN = mg
we substitute
FN = 80 × 1.0129
FN = 81.032 N { towards moon }
Therefore, the apparent weight of the astronaut is 81.032 N { towards moon }
Answer: Positive velocity is then speed towards right, and negative velocity is speed towards left. It is the same for acceleration: negative acceleration is acceleration towards left. It slows objects moving towards right
Explanation: In physics calculations, acceleration — just like displacement and velocity — can be positive or negative. can u help me now pls ?
Answer:
Tension in the chains - In a chain drive, technically, you have a closed-chain (which has no end) going around 2 pulley or gears; looking closely you have 2 parallel chains going in opposite direction. If kept in horizontal direction, the one below the other is the slack side and the other the tight side. The tension on the upper or tight side is more than the slack side. So you need to keep in mind to keep your chain drive tight so that there is no loss or rotation or lags.
Sizes of the pulley/gear - The chain will be warped around a pair of pulley or gear. The sizes of these pulley/gear will also determine the efficiency of the chain drive (consider one big and one small)
Number of pulley/gear - If the number of pulley/gear is more and chain wrapped on it with little complexity will result in decrease in efficiency because of extra tension.
Length of the chain drive - You cannot have much too long chain drive. It will make your slack side more heavy because the end are further away. You have to apply more power and possibilities of lag increases decreasing efficiency. In an ideal situation, this won't happen, but this world isn't ideal.
Friction between chains & pulley/gear - If you have studied gears (involving its teeth), you will come to know that there is friction offered on the two meeting surfaces.
Angle of contact - This would have been explained better with a diagram. Although, if you are familiar with the terms you won't have difficulty understanding. Angle of contact is the angle the chain forms with the pulley/gear at the point of contact with the center of the pulley. The angle of contact should not be too small, or else the things will be slippery.
Explanation: