What is the lift force exerted by the air on the rotors?

AI Thread Summary
To determine the lift force exerted by the air on the helicopter's rotors, apply Newton's second law, F=ma, using the combined mass of the helicopter and the car. The upward acceleration of 0.57 m/s² must be factored in, leading to a calculated lift force of approximately 4394.7 N. For the tension in the cable connecting the car to the helicopter, only the car's mass is relevant, resulting in a tension of about 3716.4 N. It's crucial to ensure that the correct mass values and acceleration are used in both calculations. Understanding these principles is essential for solving similar physics problems effectively.
thschica
Messages
47
Reaction score
0
A 6520 kg helicopter accelerates upward at 0.57 m/s2 while lifting a 1190 kg car.
(a) What is the lift force exerted by the air on the rotors?
_________ N
(b) What is the tension in the cable (ignore its mass) that connects the car to the helicopter?
_____N

I have no idea how to do this and it is going to be on my mid-term.
Can someone please help me because I keep getting very strange numbers.
I used a kinetics equation but the answer was wrong!
 
Physics news on Phys.org
Use Newtons second law: F=ma.
For (a) find out how much force is needed to accelerate both of the masses. The tension only accelerates the car.
 
If you apply Newton's Second Law to part (a) you can find the answer relatively easily; for the M value, just make sure you use the composite mass. You know a, as it's given in the question, so F can easily be solved. I think for part (b) you can just use Newton's Second Law, but remember the only mass involved is that of the suspended car. The acceleration should remain the same though...
 
should a) be 4394.7
and b) be 3716.4
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

F = ma for a lift (elevator) carrying passengers
Replies
5
Views
2K
Lifting an object, kinetic energy, work and forces
Replies
11
Views
6K
Determining Tension & Lift Force for Helicopter & Truck
Replies
6
Views
3K
What is the tension in the lift cable and in the string?
Replies
19
Views
3K
Calculating Forces in a Helicopter Lift: F=ma and Cable Tension
Replies
2
Views
2K
Calculating Lift Force for a Helicopter and Car System
Replies
9
Views
6K
Helicopter accelerates while liftin what are the forces' magnitudes?
Replies
1
Views
6K
Fluid Forces in a Manometer: Understanding Pressure and Kinetic Energy
Replies
2
Views
1K
I What is the minimum force required to lift an object?
3
Replies
128
Views
10K
Torque to lift object by cable on a drum accelerating
Replies
8
Views
4K

Hot Threads

Recent Insights

Back
Top