Answer:
t = 6 [s]
Explanation:
In order to solve this problem we must first use this equation of kinematics.
where:
Vf = final velocity = 0 (the car comes to rest)
Vo = initial velocity = 72 [km/h]
a = acceleration [m/s²]
x = distance = 60 [m]
First we must convert the velocity from kilometers per hour to meters per second.
![72 [\frac{km}{h}]*\frac{1000m}{1km} *\frac{1h}{3600s} =20 [m/s]](https://tex.z-dn.net/?f=72%20%5B%5Cfrac%7Bkm%7D%7Bh%7D%5D%2A%5Cfrac%7B1000m%7D%7B1km%7D%20%2A%5Cfrac%7B1h%7D%7B3600s%7D%20%3D20%20%5Bm%2Fs%5D)
![0=(20)^{2} -2*a*60\\400 = 120*a\\a=3.33[m/s^{2} ]](https://tex.z-dn.net/?f=0%3D%2820%29%5E%7B2%7D%20-2%2Aa%2A60%5C%5C400%20%3D%20120%2Aa%5C%5Ca%3D3.33%5Bm%2Fs%5E%7B2%7D%20%5D)
Now using this other equation of kinematics.
0 = 20-3.33*t
t = 6[s]
Answer:
UP TO four inches but usually a little slower than that
Explanation:
It causes the greenhouse effect
Answer:
B. 3
Explanation:
The half-life of a radioisotope is the time it needs for the mass of the radioisotope to halve with respect to its original value.
In this problem, the initial mass of the radioisotope at t=0 is
m0 = 50.0 mg
We see that after t = 1 min, the mass of the isotope is
m(1 min) = 25.0 mg
so, exactly half the initial mass: this means that 1 minute is exactly the half-life of this radioisotope.
So, the amount of mass left after each minute is the following:
m (1 min ) = 25.0 mg (1 half-life)
m (2 min) = 12.5 mg (2 half-lives)
m (3 min) = 6.25 mg (3 half-lives)
so, when we are left with 6.25 mg of isotope, 3 minutes have passed, which means that 3 half-lives have passed.
Answer:
Explanation:
The cross section area of the cable is
Let g = 9.81m/s2. The stress acting on the cable when mass is added is
The strain when the cable is stretched from 4.76 to 5.43 m is
So the young modulus of the cable is
