By adding the time of flight at the top of the cliff and the time taken down the hill, the ball spent 2.72 s of time in air.
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What is a Projectile ?</h3>
A projectile can be a stone or a ball or any object that can be projected. The object projected will take a trajectory path.
Given that acceleration due to gravity is 9.8 m/s and a 0.87 kg projectile is fired into the air from the top of a 8.52 m cliff above a valley. Its initial velocity is 9.1 m/s at 49◦ above the horizontal. To know how long the projectile will be in the air, we will calculate the total time of flight at the top of the cliff and the time taken down the hill
Time of flight T = 2usinФ/g
Where
Substitute all the necessary parameters into the formula
T = (2 × 9.1sin49)/ 9.8
T = 13.74/9.8
T = 1.40 s
The time taken down the cliff can be found with formula
h = ut + 1/2gt²
where u = 0
8.52 = 0 + 1/2 × 9.8 × t²
8.52 = 4.9t²
t² = 8.52/4.9
t² = 1.738
t = √1.738
t = 1.32 s
Time for the projectile in the air = T + t
Time in air = 1.40 + 1.32
Time = 2.72 s
Therefore, the projectile will be in the air for 2.72 seconds long.
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Answer:
As block 1 moves from point A to point B, the work done by gravity on block 2 is equal to the change in the kinetic energy of the two-block system.
Explanation:
As block 2 goes down , work is done by gravity on block 2 . This is converted
into kinetic energy of block 1 and block 2 . Work done by gravity is mgh which can be measured easily . kinetic energy of both the blocks can also be measured.
Answer:
The speed of the wave as it travelled through the brass bell is;
B. 4,700 m/s
Explanation:
The given parameters are;
The wavelength of the sound wave produced from the brass bell, 
= 3.5 m
The wavelength of the wave in the brass bell, 
= 47 m
The frequency of the wave in the brass bell, f = 100 Hz
The given equation for wave speed, v = f × λ
Therefore, the speed of the wave as it travelled through the brass bell, 
, is given as follows;
= f × = 100 Hz × 47 m = 4,700 m/s
The speed of the wave as it travelled through the brass bell = = 4,700 m/s
The distance traveled by pendulum, in one back-and-forth swing is 75.75 inches.
The period of pendulum can be calculated by
Where,
- period
- length = 12 inches
- gravitational acceleration = 
Put the values,
Now, the angular displacement of the pendulum can be calculated by,
Where,
- amplitude
- angle = 
- angular displacement = 
= 2.866 m
Put the values and calculate for ,
Therefore, the distance traveled by pendulum, in one back-and-forth swing is 75.75 inches.
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Indeed because some leave headlights off and ignore that fact since there are street lights around.
