That is the Sigma Symbol. It’s the addition of a sequence of numbers; the result is the sum of the total. if numbers are added sequentially from left to right, any intermediate result is a partial sum, prefix sum, or running total of the summation
The coefficient of expansion is 13 * 10^-6 m per meter length.per oK
The temperature difference = 42 - - 8 = 50 oC
delta T = (42 + 273) - (-8 + 273) = 50 oK
delta L = L * 13* 10^6 m/oK
oK = 50 oK delta L = 19.5 cm = 19.5 cm [1m / 100 cm] = 0.195m
So we need to find the length and it is computed by:
0.195= L * 13 * 10^-6 * 50 L = 0.195 / (13*10^-6*50) L = 300 m
Answer:
77.35 m / s
Ф = -17° from + X axis or 343° from + X axis
Explanation:
v1 = 75 m/s 25° east of north
v2 = 100 m/s 25° east of south
Write the velocities in vector form ,we get


Now add the velocity vectors to get the resultant of the velocities.



magnitude of resultant velocity is 
= 77.35 m / s
The direction is Ф from X axis

Ф = -17° from + X axis or 343° from + X axis
(1) The time of motion of the arrow is 0.25 s.
(2) The vertical height dropped by the arrow as it approaches the target is 0.31 m.
The given parameters:
- <em>Horizontal distance of the arrow, X = 20 m</em>
- <em>Horizontal speed of the arrow, v = 80 m/s</em>
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The time of motion of the arrow is calculated as follows;

The vertical height dropped by the arrow as it approaches the target is calculated as follows;

Learn more about time of motion of projectile here: brainly.com/question/1912408