A 900W motor is used to lift 275.51kg of bricks a distance of 30, to the roof of the building.
a. If the motor ran for 90s how much work did it do?
b. What is the potential energy of the bricks?
I know how the calculate work, but I'm really confused about how to calculate it with the time and 900W motor.
To calculate the work done by the motor, you need to understand the relationship between work, power, and time.
Work (W) is defined as the amount of energy transferred when a force is applied over a certain distance.
Power (P) is the rate at which work is done, and it is given by the formula:
P = W/t
where W is the work done and t is the time taken.
In this case, you are given the power of the motor (900W) and the time it ran (90s). We can rearrange the equation to solve for work:
W = P * t
W = 900W * 90s
W = 81000 J
Therefore, the motor did 81000 joules of work to lift the bricks.
Now, let's move on to calculating the potential energy of the bricks. The potential energy (PE) of an object is given by the formula:
PE = m * g * h
where m is the mass of the object, g is the acceleration due to gravity (9.8 m/s^2 on Earth), and h is the height that the object is lifted.
In this case, you are given the mass of the bricks (275.51 kg) and the height it is lifted (30m).
PE = 275.51 kg * 9.8 m/s^2 * 30m
PE = 808155.54 J
Therefore, the potential energy of the bricks is approximately 808155.54 joules.