<span>step 1: energy required to heat coffee
E = m Cp dT
E = energy to heat coffee
m = mass coffee = 225 mL x (0.997 g / mL) = 224g
Cp = heat capacity of coffee = 4.184 J / gK
dT = change in temp of coffee = 62.0 - 25.0 C = 37.0 C
E = (224 g) x (4.184 J / gK) x (37.0 C) = 3.46x10^4 J
step2: find energy of a single photon of the radiation
E = hc / λ
E = energy of the photon
h = planck's constant = 6.626x10^-34 J s
c = speed of light = 3.00x10^8 m/s
λ = wavelength = 11.2 cm = 11.2 cm x (1m / 100 cm) = 0.112 m
E = (6.626x10^-34 J s) x (3.00x10^8 m/s) / (0.112 m) = 1.77x10^-16 J
step3: Number of photons
3.46x10^4 J x ( 1 photon / 1.77x10^-16 J) = 1.95x10^20 photons</span>
Answer:
Speed is 0.08 m/s.
Explanation:
Given the distance that the bird flies = 3.7 meters
The time is taken by the bird to fly the 3.7 meters = 46 seconds
We have given distance and time. Now we have to find the speed at which the bird flies. So, to calculate the speed of the bird we have to divide the distance by the time.
Below is the formula to find the speed.
Speed = Distance / Time
Now insert the given value in the formula.
Speed = 3.7 / 46 = 0.08 m/s
Answer:
The acceleration is 6 [m/s^2]
Explanation:
We can find the acceleration of the roller coaster using the kinematic equation for uniformly accelerated motion.
![v_{f} =v_{i} + a*t\\where:\\v_{f} = final velocity = 22 [m/s]\\v_{i} = initial velocity = 4 [m/s]\\t = time = 3 [s]\\](https://tex.z-dn.net/?f=v_%7Bf%7D%20%3Dv_%7Bi%7D%20%2B%20a%2At%5C%5Cwhere%3A%5C%5Cv_%7Bf%7D%20%3D%20final%20velocity%20%3D%2022%20%5Bm%2Fs%5D%5C%5Cv_%7Bi%7D%20%3D%20initial%20velocity%20%3D%204%20%5Bm%2Fs%5D%5C%5Ct%20%3D%20time%20%3D%203%20%5Bs%5D%5C%5C)
Now replacing the values we have:
![a=\frac{v_{f} - v_{i} }{t} \\a=\frac{22 - 4 }{3}\\a = 6 [m/s^{2} ]](https://tex.z-dn.net/?f=a%3D%5Cfrac%7Bv_%7Bf%7D%20-%20v_%7Bi%7D%20%7D%7Bt%7D%20%5C%5Ca%3D%5Cfrac%7B22%20-%204%20%7D%7B3%7D%5C%5Ca%20%3D%206%20%5Bm%2Fs%5E%7B2%7D%20%5D)
Answer:
(a) 3.807 s
(b) 145.581 m
Explanation:
Let Δt = t2 - t1 be the time it takes from the moment when the motorcycle starts to accelerate until it catches up with the car. We know that before the acceleration, both vehicles are travelling at a constant speed. So they would maintain a distance of 58 m prior to the acceleration.
The distance traveled by car after Δt (seconds) at
speed is

The distance traveled by the motorcycle after Δt (seconds) at
speed and acceleration of a = 8 m/s2 is


We know that the motorcycle catches up to the car after Δt, so it must have covered the distance that the car travels, plus their initial distance:





(b)


The answer would be D. <span>The tortoise moved at a constant velocity throughout the race; the hare stopped to rest periodically.
Hope this helped. Good luck!</span>