Answer:
Explanation:
Let Torque due to friction be
F
Net torque
= 46 - F
Angular impulse = change in angular momentum
=( 46 - F ) x 17 = I X 580
When external torque is removed , only friction creates torque reducing its speed to zero in 120 s so
Angular impulse = change in angular momentum
F x 120 = I X 580
( 46 - F ) x 17 = F x 120
137 F = 46 x 17
F = 5.7 Nm
b )
Putting this value in first equation
5.7 x 120 = I x 580
I = 1.18 kg m²
Answer:
If the canoe heads upstream the speed is zero. And directly across the river is 8.48 [km/h] towards southeast
Explanation:
When the canoe moves upstream, it is moving in the opposite direction of the normal river current. Since the velocities are vector (magnitude and direction) we can sum each vector:
Vr = velocity of the river = 6[km/h}
Vc = velocity of the canoe = -6 [km/h]
We take the direction of the river as positive, therefore other velocity in the opposite direction will be negative.
Vt = Vr + Vc = 6 - 6 = 0 [km/h]
For the second question, we need to make a sketch of the canoe and we are watching this movement at a high elevation. So let's say that the canoe is located in point 0 where it is located one of the river's borders.
So we are having one movement to the right (x-direction). And the movement of the river to the south ( - y-direction).
Since the velocities are vector we can sum each vector, so using the Pythagoras theorem we have:
![Vt = \sqrt{(6)^{2} +(-6)^{2} } \\Vt=8.48[km/h]](https://tex.z-dn.net/?f=Vt%20%3D%20%5Csqrt%7B%286%29%5E%7B2%7D%20%2B%28-6%29%5E%7B2%7D%20%7D%20%5C%5CVt%3D8.48%5Bkm%2Fh%5D)
Answer:
1196.02 °C
Explanation:
If the kinetic energy is converted into heat,
then,
Kinetic energy of the copper = heat energy of the copper
1/2m(v²) = cm(t₂-t₁)
where m = mass of copper, v = velocity of copper, c = specific heat capacity of copper, t₂ = final temperature of copper, t₁ = initial temperature of copper.
Since the mass of copper remains the same,
1/2v² = c(t₂-t₁)
make t₂ the subject of the equation
t₂ = 1/2(v²/c)+t₁..................... Equation 1
Given: v = 950 m/s, c = 387 J/kg°C, t₁ 30 °C
Substitute into equation 1
t₂ = 1/2(950²/387)+30
t₂ = 1196.02 °C
Hence the temperature the bullet reach before it was stopped = 1196.02 °C
I think it's C, longer wave length.