Answer:
F = 274.68[N]
Explanation:
The gravitational force is equal to the weight of a body, or this case that of a person. Weight can be calculated by means of the product of mass by gravitational acceleration. In this way we have the following equation:

where:
F = force or weight [N]
m = mass = 28 [kg]
g = gravity acceleration = 9.81 [m/s²]
Now replacing:
![F=28*9.81\\F=274.68[N]](https://tex.z-dn.net/?f=F%3D28%2A9.81%5C%5CF%3D274.68%5BN%5D)
The work done by the battery is equal to the charge transferred during the process times the potential difference between the two terminals of the battery:

where q is the charge and

is the potential difference.
In our problem, the work done is W=39 J while the potential difference of the battery is

, so we can find the charge transferred by the battery:
Answer:
3kg sledgehammer swung at 1.5 m/s
Explanation:
Small Sledgehammer:
Mass:3.0
Velocity:1.5
MASS×VELOCITY=MOMENTUM
3.0×1.5= 4.5 (momentum)
Large Sledgehammer:
Mass:4.0
Velocity:0.9
4.0×0.9=3.6 (momentum)
higher momentum is the smaller Sledgehammer.