Final answer:
The equation used to calculate mass from the given work done against gravity is M = W/(g*h). With the provided values, the mass M is calculated to be 7.5 kg.
Step-by-step explanation:
Calculating Mass Using Work and Gravitational Acceleration
The student's question involves calculating the mass of an object based on work done against gravitational force. Given that work is done to lift an object a certain height, this implies that the work done (W) is equal to the gravitational potential energy (PEg) which can be calculated using the formula PEg = mgh where 'm' is the mass, 'g' is the acceleration due to gravity (9.8 m/s2), and 'h' is the height the object is lifted. This means that mass can be solved using the equation M = W/(g*h).
In the student's question, W = 29.4 J, g = 9.8 m/s2, and h = 0.4 m. Substituting these values into the equation M = W/(g*h), we get M = 29.4 J / (9.8 m/s2 x 0.4 m), which can be calculated to find the mass in kilograms.
The correct calculation is:
M = 29.4 J / (9.8 m/s2 x 0.4 m)
M = 29.4 J / 3.92 J/kg
M = 7.5 kg
Therefore, the mass of the object is 7.5 kg.