It's a bit more of a vexed question if you are considering a human body rather than an inanimate object. To lift the box requires work. An object moving at constant velocity is not being worked upon. However, you are still performing work when you move your muscles.
For knowing how an airplane flies at constant speed, follow this link: http://science.howstuffworks.com/transport/flight/modern/airplanes.htm I can't explain this in detail in writing but you can understand very well from this site
The plane will fly at steady height and speed :)
At the beginning of the lift, the lifter's force is greater than the weight of the barbell to overcome inertia and initiate movement. During the middle of the lift, the lifter's force is equal to the weight of the barbell to maintain constant velocity. Towards the end of the lift, the lifter's force is less than the weight of the barbell due to deceleration and control.
The periodic time T of a simple pendulum in a stationary lift will remain the same if the lift goes up with a uniform velocity v. The motion of a simple pendulum is independent of its surroundings as long as they do not exert any external influences on the system, such as acceleration or deceleration.
Acceleration on a lift can be calculated by dividing the change in velocity by the time taken. For example, if the lift starts from rest and accelerates to a velocity of 4 m/s in 2 seconds, the acceleration would be (4 m/s - 0 m/s) / 2 s = 2 m/s^2.
Best to start out with a weight you can lift for 10-12 reps. As you progress you can lower the reps to what feels most comfortable. Everyone is different, and some can start heavier, but 10-12 reps is a good place to start.
There are four forces act on an aircraft in flight: lift, weight, thrust, and drag. From Newton's first law of motion, if there is no net external force, the object will maintain constant velocity. i.e lift=wait , thrust=drag. This condition is called "cruise". In this situation, airplane can stay steady (constant velocity). But the weight of the aircraft is decrease a little due to fuel burned per time. If forces become unbalanced, aircraft will move by Newton's second law of motion.
For knowing how an airplane flies at constant speed, follow this link: http://science.howstuffworks.com/transport/flight/modern/airplanes.htm I can't explain this in detail in writing but you can understand very well from this site
The perfect age to build muscle is 18, but you can start working out at 16, though it is not recommended that you lift heavy weights or weights you're forcing your body to lift.
The plane will fly at steady height and speed :)
lift = 1/2 air density x velocity squared x surface area
At the beginning of the lift, the lifter's force is greater than the weight of the barbell to overcome inertia and initiate movement. During the middle of the lift, the lifter's force is equal to the weight of the barbell to maintain constant velocity. Towards the end of the lift, the lifter's force is less than the weight of the barbell due to deceleration and control.
The only relationship is that the greater the velocity of Air over a Lifting Body (Wing in general), the greater the LIFT. HOWEVER, you cannot say that the reverse is true...that is, the greater the LIFT the higher the Velocity. You can change Lift by changing the Wing DESIGN. When Landing an Airliner deploys its WING FLAPS to create greater Lift at lower velocities.
The periodic time T of a simple pendulum in a stationary lift will remain the same if the lift goes up with a uniform velocity v. The motion of a simple pendulum is independent of its surroundings as long as they do not exert any external influences on the system, such as acceleration or deceleration.
lift acts upward, and weight acts downward
LIft = coefficient times density times velocity squared times wing area divided by 2 drag= coefficient times density times velocity squared over 2 times reference area
If I were to go anywhere to get information on weight lift training I would start out at the source a gym where you can see the action first hand and get instructed. There are also so many great books out there and magazines that you could be a weight lift trainer in no time.