Answer:
To unlock a door and indicate to the person that the door is now unlocked
Explanation:
Schools all have doors locked. Visitors/parents need to press a button. That creates a buzz sound in the office, secretary presses a button to unlock the door. The person trying to enter the school hears a buzz and the secretary telling them to enter the building.
An educated guess about something. (What might happen in the future)
Complete question is;
Which of the following can be reduced to a single number in standard form?
A) 3√3 + 5√8
B) 2√5 + 5√45
C) √7 + √9
D) 4√2 + 3√6
Answer:
Only option B) 2√5 + 5√45 can be reduced to a single number
Explanation:
A) For 3√3 + 5√8;
Let's simplify it to get;
3√3 + 5√(4 × 2)
From this, we get;
3√3 + (5 × 2)√2 = 3√3 + 10√2
This is 2 numbers and not a single number. Thus it can't be reduced to a single number in standard form.
B) 2√5 + 5√45
Simplifying to get;
2√5 + 5√(9 × 5)
This gives;
2√5 + (5 × 3)√5 = 2√5 + 15√5
Adding the surds gives;
17√5.
This is a single number and thus can be reduced to a single number
C) For √7 + √9
Simplifying, to get;
√7 + 3.
This is 2 numbers and not a single number. Thus it can't be reduced to a single number in standard form.
D) 4√2 + 3√6
Thus can't be simplified further because both numbers inside the square root don't have factors that are perfect squares.
Thus, it remains 2 numbers and not a single number and can't be reduced to a single number in standard form.
Answer:

Explanation:
Mass of the bucket, m = 23 kg
Radius of the pulley, r = 0.050 m
The bucket is released from rest, u = 0 m/s
The time taken to fall, t = 2 s
Speed, v = 8.0 m/s
Moment of Inertia of the pulley, I = ?
Using the equation of motion:
v = u + at
8 = 0 + 2a
a = 8/2
a = 4 m/s²
The relationship between the linear and angular accelerations is given by the equation:

Angular acceleration, 

Since the bucket is falling, it can be modeled by the equation:
mg - T = ma
T = mg - ma = m(g-a)
T = 23(9.8 - 4)
The tension, T = 133.4 N
The equation for the pulley can be modeled by:

Answer:
Hypothesis:
When a scientist see lizard behaving in this way in each rainystrom in the desert, he can make a hypothesis about the lizard’s way of drinking water. He can say that lizard spread its legs to wide body. In this way it catches and carry water in microscopic channels on its body. These channels lead water to its mouth and it drinks this water by opening and closing mouth continuously.