Answer:
Explanation:
Since the roundabout is rotating with uniform velocity ,
input power = frictional power
frictional power = 2.5 kW
frictional torque x angular velocity = 2.5 kW
frictional torque x .47 = 2.5 kW
frictional torque = 2.5 / .47 kN .m
= 5.32 kN . m
= 5 kN.m
b )
When power is switched off , it will decelerate because of frictional torque .
Answer: 
Explanation:
Given
Radius of flywheel is 
Angular acceleration 
For no change in radius, tangential acceleration is given as
Insert the values
Answer:
Explanation:
28 / 70 = 0.3857142... = 0.39 hr
280 / 100 = 2.8 hrs.
(100 - 0) / 10 = 10 m/s²
(60 - 20) / 4 = 10 m/s²
Answer:
1 second later the vehicle's velocity will be:
5 seconds later the vehicle's velocity will be:
Explanation:
Recall the formula for the velocity of an object under constant accelerated motion (with acceleration "
"):
Therefore, in this case 
and 
so we can estimate the velocity of the vehicle at different times just by replacing the requested "t" in the expression:
Answer:
7.72 Liters
Explanation:
normal body temperature = T_body =37° C
temperature of ice water = T_ice =0°c
specfic heat of water = c_{water} =4186J/kg.°C
if the person drink 1 liter of cold water mass of water is = m = 1.0kg
heat lost by body is Qwater =mc_{water} ΔT
= mc{water} ( T_ice - T_body)
= 1.0×4186× (0 -37)
= -154.882 ×10^3 J
here negative sign indicates the energy lost by body in metabolic process energy expended due to brisk - hour long walk is Q_{walk} = 286 kilocalories
= 286×4186J
so number of liters of ice water have to drink is
n×Q_{water} =Q_{walk} n= Q_{walk}/ Q_{water}
= 286×4186J/154.882×10^3 J
= 7.72 Liters
