Answer:
174.85 W
Explanation:
Area of plate = 3.14 x (15x 10⁻²)²
= 706.5 x 10⁻⁴ m²
heat being radiated by convection = 12 x 706.5 x 10⁻⁴ ( 180 - 15 )
= 139.88 W. This energy needs to be fed by heat source to maintain a constant temperature of 180 degree.
If power of electric source is P
P x .8 = 139.88
P = 139.88 / .8
= 174.85 W
Answer:
80mm or 8cm
Explanation:
According to the lens formula,
1/f = 1/u+1/v
If the object distance u = 4cm = 40mm
Object height = 1.5mm
Image height = 3mm
First, we need to get the image distance (v) using the magnification formula Magnification = image distance/object distance = Image height/object height
v/40=3/1.5
1.5v = 120
v = 120/1.5
v = 80mm
The image distance is 80mm
To get the focal length, we will substitute the image distance and the object distance in the mirror formula to have;
1/f = 1/40+1/-80
Note that the image formed by the lens is an upright image (virtual), therefore the image distance will be negative.
Also the focal length of the converging lens is positive. Our formula will become;
1/f = 1/40-1/80
1/f = 2-1/80
1/f = 1/80
f = 80mm
The focal length of the lens 80mm or 8cm
Answer:
From the initial height h
Explanation:
When a material or substance is drop from a height h, it possesses potential energy, immediately it is dropped from that height, the potential energy is gradually converted to kinetic energy, it gets to a point where the potential energy equals the kinetic energy, as the material touches the ground, all potential energy has been converted to kinetic energy already
Answer:
Both technicians are right.
Explanation:
Torque is defined as a rotational force that can be calculated by the formula T= F.d. Being F the force applied to a body to make it rotate and d the distance since the force is applied.
So technician A is saying that gear can apply a torque to another gear, and that is true because it’s applying a rotational force to the gear next to it, in simple terms -anytime I make something rotate, I'm generating a torque-. And for technician B, the torque also can vary as a function of the distance of the force applied (size of the gear), so, it can multiply the torque and change the rotation speed.
Answer:
option c
Explanation:
K.E=1/2mv(squared)
K.E=1/2x900x80x80
K.E=450x6400=2880000J
convert to KJ=2880000/1000=2880KJ
