As our story begins, the sled ... whose mass is 8 kg ... is sliding along the ice at a speed of 4 m/s.
The sled's kinetic energy is (1/2 m v²) = (4 kg · 16 m²/s²) = 64 J .
After what seems like only the blink of an eye, the sled is no longer sliding. It is stationary. Motionless. At Rest. Just sitting there !
Its speed has been reduced to zero and ... because kinetic energy is the energy of motion ... the sled's kinetic energy is now also zero. Sixty-four Joules of energy have disappeared !
How can this be ? ! ? We know that energy is conserved. It can never just appear out of nothing, and it can never just disappear into nothing. If energy suddenly appears, it had to come from somewhere, and if energy suddenly disappears, it had to go somewhere. So where did our 64 Joules of kinetic energy go ?
It went into the ice, THAT's where ! We can say that the sled did 64J of work, and melted a thin slick layer of water on the surface of the ice. OR we can say that friction did NEGATIVE 64J of work on the sled, to cancel the 64J that it had originally, sap its kinetic energy, and bring it to rest.
I think <em>choice-B</em> was supposed to say "<em>B. -64J</em>", but somebody typed it sloppily and neglected to proofread it before posting.
The ratio of the deflection when each is connected in turns to a cell of e.m.f 25 V and internal resistance 50 ohms is 13: 12
<h3>
</h3><h3>
What is internal resistance?</h3>
Internal resistance can be described as the resistance within a battery, or other voltage source, that causes a drop in the source voltage when there is a current.
The parameters given are :
Coil 1 = 50 turns
Coil 2 = 500 turns
Resistance 1 = 1022
Resistance 2 = 6002
Internal resistance = 50 ohms
Emf = 25v
I = 25/ 50+ 10
I = 25/60
I = 5/ 12 A
= 25/50+ 600
= 25/ 650
= 5/ 130 A
The ratio of the deflection when each is connected in turns to a cell of e.m. 25 V and internal resistance 50 ohms =
Q1/ Q2
Q1 = N1 x B x 
/ c
Q2 = N2 x B x / c
therefore Q/ Q2 = (50 x 5/12 )/ (500 x 5/130)
Q1 / Q2 = 12/ 13 which 13: 12
Therefore, The ratio of the deflection when each is connected in turns to a cell of e.m. 25 V and internal resistance 50 ohms is 13: 12.
Learn more about internal resistance at; brainly.com/question/20595977
#SPJ1
Answer:Given:
Initial speed of fugitive, v0 = 0 m/s
Final speed, vf = 6.1 m/s
acceleration, a = 1.4 m/s^2
Speed of train, v = 5.0 m/s
Solution:
t = (vf-v0)/a
t = (6.1-0)/1.4
t =4.36 s
Distance traveled by train, x_T =v*t
x_T =5*4.36 = 21.8 m
Distance travelled by fugitive, x_f = v0*t+1/2at^2
x_f = 0*4.36+1/2*1.4*4.36^2
x_f =13.31 m
5*t = v(t-4.36)+x_f
5*t=6.1*(t-4.36)+13.31
solve for t, we get
t = 12.08 s
The fugitive takes 12.08 s to catch up to the empty box car.
Distance traveled to reach the box car is
X_T = v*t
X_T = 5*12.08 s
X_T = 60.4 m
Explanation:
the problems that harnessing wind for energy is the expense of large tracts of land in populated areas.
hope this helps you
