Answer:
- mass: 25.0 kg
- normal force: (boy, 53.6 N), (gravity, 245 N), (total, 298.6 N)
Step-by-step explanation:
Assuming the 50° angle is measured with respect to the horizontal, the force resolves into the (horizontal, vertical) components:
f = (70 N)(cos(50°), sin(50°)) ≈ (44.995, 53.623) N
In the horizontal direction, ...
f = ma
m = f/a = (44.995 N)/(1.8 m/s^2) = 24.997 kg
The mass of the lawnmower is about 25.0 kg.
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In the vertical direction, the force exerted by the boy is about 53.6 N. That is added to the force due to gravity, which is (25.0 kg)(9.8 m/s^2) ≈ 245.
The total normal force on the lawnmower is 53.6 N +245 N = 298.6 N.