Given:
distance from the projector lens to the image, di
projector lens focal length, f
distance from the transparency to the projector lens, do
thin lens equation: 1/f = 1/di + 1/do
do = 4 inches
di = 8 feet
convert feet to inches, for uniformity.
1 foot = 12 inches
8 feet * 12 inches/ft = 96 inches
1/f = 1/96 inches + 1/4 inches
Adding fractions, denominator must be the same.
1/f = (1/96 * 1/1) + (1/4 * 24/24)
1/f = 1/96 + 24/96
1/f = 25/96
to find the value of f, do cross multiplication
1*96 = f * 25
96 = 25f
96/25 = f
3.84 = f
The focal length of the project lens is 3.84 inches
Answer:
0.75%
Explanation:
Measured value of melting point of potassium thiocyanate = 174.5 °C
Actual value of melting point of potassium thiocyanate = 173.2 °C
<em>Error in the reading = |Experimental value - Theoretical value|</em>
<em>= |174.5 - 173.2|</em>
<em>= |1.3|</em>
<em>Percentage error = (Error / Theoretical value) × 100</em>
<em>= (1.3 / 173.2)×100</em>
<em>= 0.75 %</em>
∴ Percentage error in the reading is 0.75%
Answer:
2.03 x 10²⁴N
Explanation:
Given parameters:
Mass of moon = 7.34 x 10²²kg
Mass of the earth = 5.97 x 10²⁴kg
Distance = 3.8 x 10⁵km
Unknown:
Gravitational force of attraction = ?
Solution:
To find the gravitational force of attraction between the masses, we use the expression below;
F = 
G is the universal gravitation constant
m is the mass
1 and 2 represents moon and earth
r is the distance
F = 
F = 
= 2.03 x 10²⁴N
