Answer:
Wp = 1,272 J
Wf = -940.8 J
Wn = 0
Wg = 0
Explanation:
- Applying the definition of work, as the product of the component of the force applied, along the direction of the displacement, times the displacement, we find that due to the normal force is always perpendicular to the surface, it does no work, as it has not a component in the direction of the displacement, so Wn = 0.
- As the weight goes directly downward, it has no component in the direction of the displacement either, so Wg = 0.
- We can get the work done by the force applied P, simply as follows:
- Finally, we have the work done by the force of friction that always opposes to the displacement, so it has negative sign.
- The frictional force , can be written as follows:
where μk = coefficient of kinetic friction = 0.24
Fn = Normal Force
- In this case, since the surface is level and horizontal, and there is no acceleration of the box in the vertical direction, this means that the normal force (in magnitude) must be equal to the weight:
- Fn = m*g = 50 kg * 9.8 m/s2 = 490 N
- Replacing these values in (2), we get:
- Applying the definition of work, we can get the work done by the frictional force, as follows:
Answer: Electromagnetism and sound
Answer:
The ratio of the energy stored by spring #1 to that stored by spring #2 is 2:1
Explanation:
Let the weight that is hooked to two springs be w.
Spring#1:
Force constant= k
let x1 be the extension in spring#1
Therefore by balancing the forces, we get
Spring force= weight
⇒k·x1=w
⇒x1=w/k
Energy stored in a spring is given by 
where k is the force constant and x is the extension in spring.
Therefore Energy stored in spring#1 is, 
⇒
⇒
Spring #2:
Force constant= 2k
let x2 be the extension in spring#2
Therefore by balancing the forces, we get
Spring force= weight
⇒2k·x2=w
⇒x2=w/2k
Therefore Energy stored in spring#2 is, 
⇒
⇒
∴The ratio of the energy stored by spring #1 to that stored by spring #2 is 
2:1
The correct answer is 10 billion years. The Sun is expected to undergo hydrogen fusion for a total of 10 billion years. The Sun generates its energy by nuclear fusion of hydrogen and produces helium nucleus. It fuses 620 million metric tons every second.
Answer:
0.54 A
Explanation:
Parameters given:
Number of turns, N = 15
Area of coil, A = 40 cm² = 0.004 m²
Change in magnetic field, ΔB = 5.1 - 1.5 = 3.6 T
Time interval, Δt = 2 secs
Resistance of the coil, R = 0.2 ohms
To get the magnitude of the current, we have to first find the magnitude of the EMF induced in the coil:
|V| = |(-N * ΔB * A) /Δt)
|V| = | (-15 * 3.6 * 0.004) / 2 |
|V| = 0.108 V
According to Ohm's law:
|V| = |I| * R
|I| = |V| / R
|I| = 0.108 / 0.2
|I| = 0.54 A
The magnitude of the current in the coil of wire is 0.54 A
