Answer:
b)false
Explanation:
Rolling is a process in which work piece passes through rolls to produce desired out put of the work piece.Rolling is a metal forming process.
We know that friction force is responsible for motion of work piece between rolls.If friction force is so small at the entrance side then work piece will not enter in the forming zone and forming process will not occurs.So the friction force should be high at the entrance side and low at the exit side.
So given statement is wrong.
Answer:
b. False
Explanation:
A centimeter is a hundredth of a meter. This means 1/100 ,1 cm = 0.01 m
A kilo is 1000 grams.
The first answer is false because a hundredth isnot written well.
The second statement is false because the comparison given is of different units of measure. For distance is meters where as for weight is kilograms.
The working principle of a DC machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque that rotates the dc motor. The DC machines are classified into two types such as DC generator as well as DC motor.
Answer:
Explanation:
We use kinetic friction when a body is moving i.e.
for calculations.
Static friction is used when a body is in rest while kinetic friction is used when a body is moving and its value is quite low as compared to static friction .
Static friction value increases as we apply more force while kinetic friction occurs when there is relative motion between bodies.
Answer:
power = 49.95 W
and it is self locking screw
Explanation:
given data
weight W = 100 kg = 1000 N
diameter d = 20mm
pitch p = 2mm
friction coefficient of steel f = 0.1
Gravity constant is g = 10 N/kg
solution
we know T is
T = w tan(α + φ )
...................1
here dm is = do - 0.5 P
dm = 20 - 1
dm = 19 mm
and
tan(α) =
...............2
here lead L = n × p
so tan(α) =
α = 3.83°
and
f = 0.1
so tanφ = 0.1
so that φ = 5.71°
and now we will put all value in equation 1 we get
T = 1000 × tan(3.83 + 5.71 )
T = 1.59 Nm
so
power =
.................3
put here value
power =
power = 49.95 W
and
as φ > α
so it is self locking screw