Answer:

Explanation:
Let the distance moved by Joe is "d"
so the time taken by him to drove it by speed 45 mph is given as


now the same distance is traveled by him with speed 55 mph
so the time taken by him

so total time taken by him for complete distance 2d



now the average speed is given as



Hello,
I believe they are a lever and a wedge.
I hope this helps!
It is important to note that the electromagnetic spectrum has a variety of wavelength and frequency of light in it. Some lights we can see, while others are not visual to our naked eye. It is actually very important to determine the kind of light as different lights have different wavelengths and frequencies. some lights are of very high frequency like the gamma rays, while others are of far lower frequency. <span />
Answer:
the answer is A. A school crossing guard raises a stop sign that weigh 10 N
Answer:
a) v=2.743m/s
b) 
c) T=2.543N
Explanation:
First, calculate the height of the ball at the starting point:


At this point, just in the moment the ball is released, all the energy of the system is potencial gravitational energy. When it is at the bottom all the potencial energy is transformed into kinetic energy:

Solving for v:

if h is the height loss: (l-y')
v=2.743m/s
The centripetal acceleration is the acceleration caused by the tension force exercised by the string, and is pointing outside of the trayectory path (at the lowest point, directly dawn):


To calculate tension, just make the free body diagram of forces in the ball, noticing the existence of the centripetal acceleration:
