Answer:
13.95
Explanation:
Given :
Vector A polar coordinates = ( 7, 70° )
Vector B polar coordinates = ( 4, 130° )
To find A . B we will
A ( r , ∅ ) = ( 7, 70 )
A = rcos∅ + rsin∅
therefore ; A = 2.394i + 6.57j
B ( r , ∅ ) = ( 4, 130° )
B = rcos∅ + rsin∅
therefore ; B = -2.57i + 3.06j
Hence ; A .B
( 2.394 i + 6.57j ) . ( -2.57 + 3.06j ) = 13.95
Answer: hello some parts of your question is missing attached below is the missing information
The radiator of a car is a type of heat exchanger. Hot fluid coming from the car engine, called the coolant, flows through aluminum radiator tubes of thickness d that release heat to the outside air by conduction. The average temperature gradient between the coolant and the outside air is about 130 K/mm . The term ΔT/d is called the temperature gradient which is the temperature difference ΔT between coolant inside and the air outside per unit thickness of tube
answer : Total surface area = 3/2 * area of old radiator
Explanation:
we will use this relation
K = 
change in T = ΔT
therefore New Area ( A ) = 3/2 * area of old radiator
Given that the thermal conductivity is the same in the new and old radiators
A vector is a phenomenon which in mostly used in mathematics and physics and is related to direction and size.
<u>Explanation:</u>
In mathematics and physics, a vector is a component of a vector space. For some, particular vector spaces, the vectors have gotten explicit names, which are recorded beneath. Verifiably, vectors were presented in geometry and material science before the formalization of the idea of vector space.
A vector is an amount or phenomenon that has two autonomous properties: magnitude and direction. The term likewise means the numerical or geometrical portrayal of such an amount.
Answer:
t = 25.10 sec
Explanation:
we know that Avrami equation

here Y is percentage of completion of reaction = 50%
t is duration of reaction = 146 sec
so,


taking natural log on both side
ln(0.5) = -k(306.6)

for 86 % completion




t = 25.10 sec