Answer:
170 N
Explanation:
Given in the question that, work a bulldozer can do = 4500 J
<h3>
Step 1</h3>
We will use trigonometry identity to find the distance bulldozer will travel up the hill
sin(35) = opp/hypo
sin(35) = 15/hypo
hypo = 15/sin(35)
hypo = 26.15m
<h3>Step 2</h3>
Formula to use
work done = force × distance
Plug values in the above formula
4500 = force x 26.15
force = 4500/26.15
force = 172.08
force ≈ 170 N
<h3 /><h3 /><h3 />
Answer:D
Explanation:
Given
mass of object 
Distance traveled 
velocity acquired 
conserving Energy at the moment when object start falling and when it gains 12 m/s velocity
Initial Energy
Final Energy

where
is friction work if any


Since Friction is Present therefore it is a case of Open system and net external Force is zero
An open system is a system where exchange of energy and mass is allowed and Friction is acting on the object shows that system is Open .