Vf = final velocity
vo = initial velocity
a = acceleration
t = time
use the following equation
vf = vo + at
since vo = 0 m/s (stopped), that term drops out and you're left with . . .
vf = at
(60 m/s) = (8.0 m/s²)t
t = (60 m/s)/(8.0 m/s²) = 7.5 seconds
<u><em>t = 7.5 seconds</em></u>
Answer:
v = 31.32 [m/s]
Explanation:
To solve this problem we must use the principle of energy conservation, which tells us that potential energy is converted into kinetic energy or vice versa. The potential energy can be calculated by the product of mass by gravity by height.

where:
Epot = potential energy [J]
m = mass = 25 [kg]
g = gravity acceleration = 9.81 [m/s²]
h = elevation = 50 [m]
Now replacing:
![E_{pot}=25*9.81*50\\E_{pot}= 12262.5[J]](https://tex.z-dn.net/?f=E_%7Bpot%7D%3D25%2A9.81%2A50%5C%5CE_%7Bpot%7D%3D%2012262.5%5BJ%5D)
When the rock falls the potential energy is converted into kinetic energy.

where:
Ek = kinetic energy [J]
v = velocity [m/s]
Now clearing v:
![v^{2} =\frac{E_{k}*2}{m}\\v=\sqrt{(2*12262)/25}\\v = 31.32 [m/s]](https://tex.z-dn.net/?f=v%5E%7B2%7D%20%3D%5Cfrac%7BE_%7Bk%7D%2A2%7D%7Bm%7D%5C%5Cv%3D%5Csqrt%7B%282%2A12262%29%2F25%7D%5C%5Cv%20%3D%2031.32%20%5Bm%2Fs%5D)
Answer:
L2 = 1.1994 m
the length of the pendulum rod when the temperature drops to 0.0°C is 1.1994 m
Explanation:
Given;
Initial length L1 = 1.2m
Initial temperature T1 = 27°C
Final temperature T2 = 0.0°C
Linear expansion coefficient of brass x = 1.9 × 10^-5 /°C
The change i length ∆L;
∆L = L2 - L1
L2 = L1 + ∆L ...........1
∆L = xL1(∆T)
∆L = xL1(T2 - T1) ......2
Substituting the given values into equation 2;
∆L = 1.9 × 10^-5 /°C × 1.2m × (0 - 27)
∆L = 1.9 × 10^-5 /°C × 1.2m × (- 27)
∆L = -6.156 × 10^-4 m
From equation 1;
L2 = L1 + ∆L
Substituting the values;
L2 = 1.2 m + (- 6.156 × 10^-4 m)
L2 = 1.2 m - 6.156 × 10^-4 m
L2 = 1.1993844 m
L2 = 1.1994 m
the length of the pendulum rod when the temperature drops to 0.0°C is 1.1994 m
Refractive index (symbol n) is defined as the ratio of the velocity of light in a vacuum (symbol c) to the velocity of light in a medium (symbol v). The equation is n=c/v. In order to obtain the speed of light in carbon disulphide the above equation needs to be rearranged to make v the subject. This yields v=c/n. Plugging the numbers in yields a speed to 1.84x10^8 metres per second.