Respuesta :
Answer:
a) The work done in raising the block up to 2.0 m is 137.2 joules
b) The power exerted by the string in pulling the box up the ramp is 68.6 watts
Explanation:
The question examines the relationship between work energy and power
The parameters of the pulled box are;
The mass of the box, m = 7.0 kg
The height to which the box is pulled, h = 2.0 m
The velocity at which the box is moving at the 2.0 m height = 6.0 m/s
The time if takes the box to reach the height of 2.0 m = 2.0 seconds
The acceleration due to gravity, 'g' is taken as approximately 9.8 m/s²
a) The work done in raising the block up to 2.0 m = The potential energy gained by the block
The potential energy gained by the block, P.E. = m·g·h
Therefore, we have;
The work done in raising the block up to 2.0 m = P.E. = m·g·h
By substituting the given values, we get;
The work done in raising the block up to 2.0 m = 7.0 kg × 9.8 m/s² × 2.0 m = 137.2 joules
b) Power = The rate of doing work
∴ Power, P = Work done/(Time takes for the work)
The work done in raising the block up to 2.0 m = 137.2 joules
The time if takes the box to reach the height of 2.0 m = 2.0 seconds
∴ The power exerted by the string in pulling the box up the ramp, 'P' is given as follows;
P = 137.2 joules/(2.0 seconds) = 68.6 watts
The power exerted by the string in pulling the box up the ramp, P = 68.6 watts.
