Mr. Cohen is a scientist who is testing the efficiency of a 9 V battery by measuring how much electrical energy it releases. He
1 answer:
Answer:
D. (7 ÷ 9) × 100
Explanation:
In order to solve this problem we need the answers of the problem, performing an internet search this problem is found, with the different answer options
A. (7 − 9) × 100
B. (9 − 7) × 100
C. (9 ÷ 7) × 100
D. (7 ÷ 9) × 100
Returning to the problem of the total energy of 9V only 7 volts were used. If we make a rule of three we realize that:
x = 77.77%
In this way we determine that the answer is D.
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Answer:
A)s = 104.16 m
b)s= 104.16 m
Explanation:
Given that
u = 25 m/s
μ = 0.3
The friction force will act opposite to the direction of motion.
Fr= μ m g
Fr= - m a
a=acceleration
μ m g = - m a
a= - μ g
a= - 0.3 x 10 m/s² ( take g= 10 m/s²)
a= - 3 m/s²
The final speed of the mass is zero ,v= 0
We know that
v² = u² +2 a s
s=distance
0² = 25² - 2 x 3 x s
625 = 6 s
s = 104.16 m
By using energy conservation
Work done by all the forces =Change in the kinetic energy
Negative sign because force act opposite to the displacement.
- 3 x 2 x s = - 625
s= 104.16 m
Answer:
v= 1.71 m/s
Explanation:
Given that
Distance between two successive crests = 4.0 m
λ = 4 m
T= 7 sec
T is the time between 3 waves.
3 waves = 7 sec
1 wave = 7 /3 sec
So t= 7/3 s
We know that frequency f
f= 1/t= 3/7 Hz
Lets take speed of the wave is v
v= f λ
f=frequency
λ=wavelength
v= 3/7 x 4 = 12 /7
v= 1.71 m/s
