Consider an acrylic sheet of thickness L = 5 mm that is used to coat a hot, isothermal metal substrate at Th = 300°C. The proper
ties of the acrylic are rho = 1990 kg/m3, c = 1470 J/kg · K, and k = 0.21 W/m · K. Neglecting the thermal contact resistance between the acrylic and the metal substrate, determine how long it will take for the insulated back side of the acrylic to reach its softening temperature, Tsoft = 90°C. The initial acrylic temperature is Ti = 20°C.
1 answer:
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Answer:
(a)
(b)
Solution:
As per the question:
Side of the cube, a = 4.4 cm
Coordinates of the diagonally opposite corner, A = <4.4, 4.4, 4.4> cm
Now,
(a) To calculate the unit vector:
(b) To calculate the angle between the two vectors say A and A' is given by:
(1)
Now,
The coordinates of the diagonally opposite corner, A' is <0, 0, 1> cm
Thus
Now,
Using equation (1) :
Thus
Answer:
Explanation:
Let consider a car travelling at a speed . The ratio of final kinetic energy to initial kinetic energy:
The final speed is:
Answer:
a) = 4.67m/s
b) V = 8.29 m/s
Explanation:
Givens:
The bullet is 5.30g moving at 963m/s and its speed reduced to 426m/s. The wooden block is 610g.
a) From conservation of linear momentum
Pi = Pf
where are the mass and the initial velocity of the bullet,
and
are the mass and the initial velocity of the wooden block, and
and
are the final velocities of the wooden block and the bullet
The wooden block is initial at rest this yields
By solving for adn substitute the givens
=
=
= 4.67m/s
b) The center of mass speed is defined as
substituting:
V = 8.29 m/s