Answer:


Explanation:
We have an uniform circular motion, therefore, the pebble’s speed is given by the distance traveled in a revolution
and the period (T), since this is the time pebble’s takes to complete a revolution:

The period is inversely proportional to the frequency:

So, we have:

Recall that the radius is the half of the diameter and one revolution per is equal to one Hz:

The centripetal acceleration is defined as:

Answer:
80 Joules.
Explanation:
Given that a 20 kg sled stars at the top of a hill which is 10 m above the bottom and slides a distance of 50 m, ending at the bottom of the hill with a speed of 8 m/s. During the slide, the work done by gravity is about ?
The parameters given are:
Mass M = 20 kg
Height h = 10 m
Velocity V = 8 m/s
The workdone by gravity will be equal to the total energy
At the bottom of the hill, the total energy will be equal to the maximum kinetic energy.
Maximum K.E = 1/2mv^2
K.E = 1/2 × 20 × 8
K.E = 80J
Therefore, the workdone by the gravity is equal to 80 Joules.
initial acceleration of rocket is given as
a = 12 m/s^2
h = 26 m
now we can use kinematics to find its speed



now after this it will be under free fall
so now again using kinematics

at maximum height



total height from the ground = 31.8 + 26 = 57.8 m
Part b)
now after reaching highest height it will fall to ground
So in order to find the speed we can use kinematics again



Part c)
first rocket accelerate to reach height 26 meter and speed becomes 24.98 m/s
now we have



after this it will reach to highest point and final speed becomes zero



now from this it will fall back to ground and reach to final speed 33.67 m/s
now we have



so total time is given as
<em>t = 3.44 + 2.55 + 2.1 = 8.1 s</em>
Air pressure is the amount of molecules in the air. For example, the higher you go in Earth's atmosphere the less pressure so less molecules. <span />