Ox:vₓ=v₀
x=v₀t
Oy:y=h-gt²/2
|vy|=gt
tgα=|vy|/vₓ=gt/v₀=>t=v₀tgα/g
y=0=>h=gt²/2=v₀²tg²α/2g=>tgα=√(2gh/v₀²)=√(2*10*20/24²)=√(400/576)=0.83=>α=tg⁻¹0.83=39°
cosα=vₓ/v=v₀/v=>v=v₀/cosα=24/cos39°=24/0,77=31.16 m/s
Ec=mv²/2=2*31.16²/2=971.47 J=>Ec≈0.97 kJ
Answer:
-320 μJ.
Explanation:
Consider a point with an electrical charge of
. Assume that
is the electrical potential at the position of that charge. The electrical potential of that point charge will be equal to:
.
Keep in mind that since both
and
might not be positive, the size of the electrical potential energy might not be positive, either.
For this point charge,
; (that's -8.0 microjoules, which equals to
)
.
Hence its electrical potential energy:
.
Why is this value negative? The electrical potential energy of a charge is equal to the work needed to bring that charge from infinitely far away all the way to its current position. Also, negative charges are attracted towards regions of high electrical potential. Bringing this
negative charge to the origin will not require any external work. Instead, this process will release 320 μJ of energy. As a result, the electrical potential energy is a negative value.
Answer:
a) 42 m/s, positive direction (to the east), b) 42 m/s, negative direction (to the west).
Explanation:
a) Let consider that Car A is moving at positive direction. Then, the relative velocity of Car A as seen by the driver of Car B is:

42 m/s, positive direction (to the east).
b) The relative velocity of Car B as seen by the drive of Car A is:

42 m/s, negative direction (to the west).
<span>When a magnet moves near a wire, it's changing field causes the electrons in the wire to flow as electric current.</span>
R = 1.4GΩ.
The relation between the resistance and the resistivity is given by the equation R = ρL/A, where ρ is the resistivity of a given material, L is the length and A is the cross-sectional area of the material.
To calculate the resistance of a wire of L = 2m, ρ = 49x10⁴Ω.m and A = 0.7mm² = 0.7x10⁻³m² we have to use the equation R = ρL/A.
R = [(49x10⁴Ω.m)(2m)/0.7x10⁻³m²
R = 98x10⁴Ω.m²/0.7x10⁻³m²
R = 1.4x10⁹Ω = 1.4GΩ