solution:
Answer:
425.1 W
Explanation:
We are given;
Counter mass of elevator; m_c = 940 kg
Cab mass of elevator; m_d = 1200 kg
Distance from rest upwards; d = 35 m
Time to cover distance; t = 3.5 min
Now, this elevator will have 3 forces acting on it namely;
Force due to the counter weight of the elevator; F_c
Force due to the cab weight on the elevator; F_d
Force exerted by the motor; F_m
Now, from Newton's 2nd law of motion,
The force exerted by the motor on the elevator can be given by the relationship;
F_m = F_d - F_c
Now,
F_d = m_d × g
F_d = 1200 × 9.81
F_d = 11772 N
F_c = m_c × g
F_c = 940 × 9.81
F_c = 9221.4 N
Thus;
F_m = 11772 - 9221.4
F_m = 2550.6 N
Now, the average power required of the force the motor exerts on the cab via the cable is given by;
P_m = F_m × v
Where v is the velocity of the elevator.
The velocity is calculated from;
v = distance/time
v = 35/3.5
v = 10 m/min
Converting to m/s gives;
v = 10/60 m/s = 1/6 m/s
Thus;
P_m = 2550.6 × 1/6
P_m = 425.1 W
Let's take east and west to be positive and negative, respectively, and north and south to be positive and negative, respectively. Then in terms of vectors (using ijk notation), the car first moves 200 km west,
r = (-200 km) j
then 80 km southwest,
s = (-80/√2 km) i + (-80/√2 km) j
so that its total displacement is
r + s = (-80/√2 km) i + ((-200 - 80/√2) km) j
r + s ≈ (-56.6 km) i + (-256.6 km) j
This vector has magnitude
√((-56.6 km)² + (-256.6 km)²) ≈ 262.7 km
and direction θ such that
tan(θ) = (-256.6 km) / (-56.6 km) ==> θ ≈ -102.4º
relative to east, or about 12.4º west of south.
Answer:
69.68 N
Explanation:
Work done is equal to change in kinetic energy
W = ΔK = Kf - Ki =
W =
where m = mass of the sprinter
vf = final velocity
vi = initial velocity
W = workdone
kf = final kinetic energy
ki = initial kinetic energy
d = distance traveled
Ftotal = total force
vf = 8m/s
vi= 2m/s
d = 25m
m = 60kg
inserting parameters to get:
W = ΔK = Kf - Ki =
= 39.7
we know that the force the sprinter exerted F sprinter, the force of the headwind Fwind = 30N
Answer:
Force exerted by sprinter = 69.68 N
Explanation:
From work energy theorem, we know that, work done is equal to change in kinetic energy.
Thus,
W = ΔK = Kf - Ki = (1/2)m•(v_f)² - (1/2)m•(v_i)² - - - - eq(1)
Now,
Work done is also;
W = Force x Distance = F•d - - - (2)
From the question, we are given ;
v_f = 6 m/s
v_i = 2 m/s
d = 25m
m = 62 kg
Equating equation 1 and 2,we get;
(1/2)m•(v_f)² - (1/2)m•(v_i)² = F•d
Plugging in the relevant values to obtain ;
(1/2)(62)[(6)² - (2)²] = F x 25
31(36 - 4) = 25F
992 = 25F
F = 39.68 N
The force the sprinter exerts backward on the track will be the sum of this force and the headwind force.
Thus,
Force of sprinter = 39.68 + 30 = 69.68N
To solve this problem it is necessary to apply Snell's law and thus be able to calculate the angle of refraction.
From Snell's law we know that
Where,
n_i = Refractive indices of each material
= Angle of incidence
= Refraction angle
Our values are given as,
Replacing
Re-arrange to find
Therefore the angle will the beam make with the normal in the glass is 26°
Explanation:
Using table A-3, we will obtain the properties of saturated water as follows.
Hence, pressure is given as p = 4 bar.
= 2553.6 kJ/kg
At state 2, we will obtain the properties. In a closed rigid container, the specific volume will remain constant.
Also, the specific volume saturated vapor at state 1 and 2 becomes equal. So,
According to the table A-4, properties of superheated water vapor will obtain the internal energy for state 2 at and temperature so that it will fall in between range of pressure p = 5.0 bar and p = 7.0 bar.
Now, using interpolation we will find the internal energy as follows.
= 2963.2 - 2.005
= 2961.195 kJ/kg
Now, we will calculate the heat transfer in the system by applying the equation of energy balance as follows.
Q - W = ......... (1)
Since, the container is rigid so work will be equal to zero and the effects of both kinetic energy and potential energy can be ignored.
= 0
Now, equation will be as follows.
Q - W =
Q - 0 =
Q =
Now, we will obtain the heat transfer per unit mass as follows.
= (2961.195 - 2553.6)
= 407.595 kJ/kg
Thus, we can conclude that the heat transfer is 407.595 kJ/kg.
The heat transfer is 227.4 kJ per kg of water.
Water, initially saturated vapor at 4 bar, fills a closed, rigid container. The water is heated until its temperature is 360°C. To determine the heat transfer in kJ per kg of water, we need to calculate the heat absorbed by the water as it reaches 360°C.
Using the specific heat capacity of water (4,186 J/kg°C) and the change in temperature (360°C - 100°C), we can calculate the heat transfer:
Qw = mw * cw * AT = (1 kg) * (4186 J/kg°C) * (360°C - 100°C) = 227,440 J = 227.4 kJ
Therefore, the heat transfer is 227.4 kJ per kg of water.
Heat transfer is the process by which thermal energy moves from one object or substance to another due to a difference in temperature. This fundamental phenomenon occurs through three main mechanisms: conduction, convection, and radiation. Conduction involves the direct transfer of heat through a material, such as metal. Convection is the transfer of heat through the movement of fluids (liquids or gases). Radiation is the emission of electromagnetic waves carrying heat energy. Understanding heat transfer is essential in various fields, including physics, engineering, and environmental science, as it governs temperature regulation, climate dynamics, and the functioning of countless technological devices.
#SPJ3
The average momentum of the bird (in unit vector notation) is (0.1842i + 0.1842j) kgm/s.
Since the unladen swallow that weighs 0.03 kg flies straight northeast (that is at a bearing of 45°) a distance of 125 km in 4.0 hours.
Its position vector after 4.0 hours is d = (125kmcos45)i + (125kmsin45)j = (125000 × 1/√2)i + (125000 × 1/√2)j
= (62500√2)i + (62500√2)j.
If the initial position of the swallow is d' = 0i + 0j, then its total displacement after 4 hours is, D = d - d'
= (62500√2)i + (625000√2)j - (0i + 0j)
= (62500√2)i + (62500√2)j m
The unladen swallow's average velocity, v = D/t where
So, v = [(62500√2)i + (62500√2)j m]/14400 s = (88388.35)i/14400 + (88388.35)j /1440
= 6.14i + 6.14j m/s
The average momentum of the unladen swallow is p = mv where
So, p = mv
p = 0.03 kg × (6.14i + 6.14j m/s)
p = (0.1842i + 0.1842j) kgm/s
So, the average momentum of the bird (in unit vector notation) is (0.1842i + 0.1842j) kgm/s.
Learn more about average momentum here:
Answer:
The average momentum of the bird is 0.26 kgm/s
Explanation:
The formula to be used here is that of momentum which is
momentum (in kgm/s) = mass (in kg) × velocity (in m/s)
The velocity of the bird is
velocity (in m/s) = distance (in meter) ÷ time (in seconds)
distance in meters = 125km × 1000 = 125,000 m
time in seconds = 4 hrs × 60 × 60 = 14,400 secs
velocity = 125000/14400
velocity = 8.68 m/s
momentum (p) = 0.03 × 8.68
p = 0.26 kgm/s
The average momentum of the bird is 0.26 kgm/s