Answer:
As follows,
Explanation:
KE=1/2mv^2
In 1st question,
KE=1/2mv^2=1/2*0.05*12=0.3 J [50g=0.05 kg]
In 2nd question,
KE=1/2mv^2
6.8=1/2*0.046*v^2
v=sqrt(6.8/0.023)
v=17.19
In 3rd question,
KE=1/2mv^2
63/392=m
m=0.16kg=160g
For 4th,
a.
1st case,
KE=1/2mv^2=1/2*28*2.4^2=80.64
2nd case,
KE=1/2mv^2=1/2*28*3.7^2=191.66
Change in KE=191.66-80.64=11.02
b.Speed/velocity gained
Magnets don’t need to touch each other in order to be magnetic because all objects have an attraction however, the closer the magnets get, the more magnetic it is.
Answer:
the power that must be supplied to the motor is 101.45 hp
Explanation:
Given that,
The weight of elevator = 1000lb
The motor exerts a constant force of 500 lb on the cable
The load has been hoisted s = 15 ft starting from rest
The motor has an efficiency of e = 0.65
According to the equation of motion:
F = ma


To calculate the output power:
P(out) = F. v
P(out) = 3 (500) * 21.98
P(out) = 32970 lb.ft/s
As efficiency is given and output power is known, we can calculate the input power.
ε = P(out) / P(in)
0.65 = 32970 / P(in
)
P(in) = 50,723 lb.ft/s
P(in) = 50,723 / 500 hp
= 101.45 hp
the power that must be supplied to the motor is 101.45 hp