Answer:
The work done against friction is the work done on an object that overcomes this frictional force allowing the object to move - it doesn't include any extra work used to accelerate an object for example - only the work used to beat the frictional force.
Explanation:
Air resistance opposes the motion of falling objects. Dense air prefers to stay at low heights. More dense the air is, more air resistance it produces. Hence acceleration of falling objects decreases. Hope this helps!
Answer:
Explanation:
Let us study the downward movement of cylinder which accelerates as well as rotates .
A)
If v be the linear downward velocity of cm of cylinder and ω be angular velocity of cylinder
v = ωr , when there is no slippage of string around cylinder.
B &C )
Total kinetic energy = Rotational + linear
= 1/2 Iω² + 1/2 m v²
1/2 x1/2 mr²ω² +1/2 m v²
= 1/4 mv² +1/2 m v²
= 3/4 m v²
For downward acceleration ,
mg - T = ma where T is tension in string.
Rotational movement
Torque = T x r
Tr = I α , I is moment of inertia and α is angular acceleration .
= I a/r
T = I a / r² , Putting this value of T in earlier equation
mg - I a / r² = ma
a (I / r² +m )= mg
a = mg / (I / r² +m )
For cylinders
I = .5 mr²
a = g / (.5 +1)
= g / 1.5
