Matter expands when it gets hotter
Answer:
Torque decreases .
Explanation:
The tape is pulled at constant speed , speed v is constant , so there is
v = ω r where ω is angular speed and r is radius , As radius decreases , angular speed ω increases , So there is angular acceleration .
Let it be α . Let I be moment of inertia of reel .
Reel is in the form of disc
I = 1/2 m r²
I x α = torque
1/2 m r² x α = torque
As the reel is untapped , its mass decreases , r also decreases , so torques also decreases .
Answer:
radiated heat from the Sun being absorbed by the ground
Given
m1(mass of red bumper): 225 Kg
m2 (mass of blue bumper): 180 Kg
m3(mass of green bumper):150 Kg
v1 (velocity of red bumper): 3.0 m/s
v2 (final velocity of the combined bumpers): ?
The law of conservation of momentum states that when two bodies collide with each other, the momentum of the two bodies before the collision is equal to the momentum after the collision. This can be mathemetaically represented as below:
Pa= Pb
Where Pa is the momentum before collision and Pb is the momentum after collision.
Now applying this law for the above problem we get
Momentum before collision= momentum after collision.
Momentum before collision = (m1+m2) x v1 =(225+180)x 3 = 1215 Kgm/s
Momentum after collision = (m1+m2+m3) x v2 =(225+180+150)x v2
=555v2
Now we know that Momentum before collision= momentum after collision.
Hence we get
1215 = 555 v2
v2 = 2.188 m/s
Hence the velocity of the combined bumper cars is 2.188 m/s
The heat energy lost or gained by a substance is given by the equation
Q = mCΔT, where
Q is the heat energy gained or lost by a substance,
m is mass (in grams),
C is the specific heat of the substance,
ΔT is the change in temperature (final temperature - initial temperature).
The joules given off by 617 grams of water cooling from 65°C to 28°C, given the specific heat of water as Cw=4.186 J/g*Co, is:
Q = mCwΔT
Q = (617)(4.186)(28 - 65)
Q = -95562.194
Negative means heat is lost, so 96000 J of heat was lost.