kinetic energy and net force
The weight lifter needs to apply force to the barbells and move them over a distance in the direction of the force being applied. Work is calculated as force multiplied by distance, so by exerting force to lift the barbells overhead, the weight lifter is performing work against gravity.
When a weight lifter holds barbells above his head, he uses his muscles to contract and generate force, allowing him to lift and stabilize the weight. This involves the activation of various muscle groups, such as the deltoids, triceps, and core muscles, to perform the work of lifting and holding the barbells overhead.
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 forces acting on the weight lifter and the weights are balanced when the weight lifter is holding the weights stationary. The force exerted by the weight lifter is equal and opposite to the force of gravity acting on the weights.
If the dumbbell does not move, then the work done by the weight lifter is zero. This is because work is defined as force applied over a distance in the direction of the force, and if there is no movement, no work is done.
The weight lifter needs to apply force to the barbells and move them over a distance in the direction of the force being applied. Work is calculated as force multiplied by distance, so by exerting force to lift the barbells overhead, the weight lifter is performing work against gravity.
When a weight lifter holds barbells above his head, he uses his muscles to contract and generate force, allowing him to lift and stabilize the weight. This involves the activation of various muscle groups, such as the deltoids, triceps, and core muscles, to perform the work of lifting and holding the barbells overhead.
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 forces acting on the weight lifter and the weights are balanced when the weight lifter is holding the weights stationary. The force exerted by the weight lifter is equal and opposite to the force of gravity acting on the weights.
If the dumbbell does not move, then the work done by the weight lifter is zero. This is because work is defined as force applied over a distance in the direction of the force, and if there is no movement, no work is done.
(using squats for the sake of explanation) The lifter exerts an action force on the weight, which is in the opposite direction to gravity. The lifters shoulders also experience the reaction force (from the weight - otherwise, the weight would pass through the lifter or vice versa). The feet of the lift also experience a reaction force, which, combined with the shoulder-reaction force, is equal to the action force (Newton's Third Law). The feet also experience friction on the floor surface in opposite directions (which cancel out, so the lifter is stationary on the ground) :)
(using squats for the sake of explanation) The lifter exerts an action force on the weight, which is in the opposite direction to gravity. The lifters shoulders also experience the reaction force (from the weight - otherwise, the weight would pass through the lifter or vice versa). The feet of the lift also experience a reaction force, which, combined with the shoulder-reaction force, is equal to the action force (Newton's Third Law). The feet also experience friction on the floor surface in opposite directions (which cancel out, so the lifter is stationary on the ground) :)
(using squats for the sake of explanation) The lifter exerts an action force on the weight, which is in the opposite direction to gravity. The lifters shoulders also experience the reaction force (from the weight - otherwise, the weight would pass through the lifter or vice versa). The feet of the lift also experience a reaction force, which, combined with the shoulder-reaction force, is equal to the action force (Newton's Third Law). The feet also experience friction on the floor surface in opposite directions (which cancel out, so the lifter is stationary on the ground) :)
The work done by the weight lifter holding a weight of 80 kg on his shoulder for 2 minutes is zero, assuming he remains stationary. Work is calculated as force multiplied by displacement in the direction of the force, and since there is no displacement in this case, no work is done.
The force exerted by the weight of the air above is called atmospheric pressure.
The work done would be zero, since the weight lifter is not moving the weight vertically. Work is defined as force applied in the direction of motion. Holding a weight in a static position does not result in any work being done.
The force exerted by the weight of the air above is called atmospheric pressure. It is the pressure exerted on Earth's surface by the weight of the air in the atmosphere above it.