A 1-kg block is lifted vertically 1m by a boy. The work done by the boy would be one jule or would no work be done. I'm confused, I thought lifting wasn't considered work.
The work done is actually about 9.81 joules. Think of gravity pulling on the block as an invisible string connecting the block to the Earth. If you lift the block you store energy in the gravitational field (you "strech the string" a bit more) which you can release by dropping the block.
You are correct, Count.
Poor answer
Actually, lifting a block vertically does require work to be done. In simple terms, work is defined as the transfer of energy that occurs when a force is applied to an object, causing it to move in the direction of the force. The formula for work is:
Work = Force × Distance × cos(θ)
In this case, the force being applied is the force required to lift the block against gravity, which is equal to the weight of the block. The weight of an object is given by the formula:
Weight = mass × acceleration due to gravity
In this scenario, the mass of the block is 1 kg and the acceleration due to gravity is approximately 9.81 m/s². Therefore, the weight of the block is:
Weight = 1 kg × 9.81 m/s² = 9.81 N
The distance the block is lifted vertically is 1 meter. Plugging these values into the work formula, we have:
Work = 9.81 N × 1 m × cos(θ)
Since the block is being lifted vertically, the angle θ between the applied force and the direction of motion is 0 degrees, and cos(0) equals 1. Therefore, the work done by the boy in lifting the block is:
Work = 9.81 N × 1 m × 1 = 9.81 joules
So, the work done by the boy in lifting the 1-kg block vertically by 1 meter would be approximately 9.81 joules. It's important to note that lifting an object against gravity always involves doing work, as you are transferring energy to the object and increasing its potential energy.
Actually, lifting an object vertically does require work to be done. Work is defined as the transfer of energy that occurs when a force is applied to an object and the object moves a certain distance in the direction of the force.
In this case, the boy exerts a force on the block to lift it vertically. The force he exerts is equal to the weight of the block, which can be calculated using the formula F = m * g, where m is the mass of the block and g is the acceleration due to gravity (approximately 9.8 m/s^2).
The work done is then given by the formula W = F * d, where F is the force applied and d is the distance over which the force is applied. In this case, the force is equal to the weight of the block and the distance is 1 meter.
So, the work done by the boy in lifting the 1-kg block vertically 1 meter would be W = (1 kg) * (9.8 m/s^2) * (1 m) = 9.8 joules.
Therefore, the correct answer is that the work done by the boy is 9.8 joules, not 1 joule.