Answer:Friction force
Explanation:
The frictional force is responsible for stopping the moving object.
The friction force is provided by nature in the form of air resistance, fluid resistance, Surface resistance.
For surface resistance, the friction force is of two types namely kinetic friction force and static friction force.
Static friction acts when the object is stationary and a force is applied to cause the motion while kinetic friction acts when the body starts moving.
kinetic friction is lesser is in magnitude as compared to static friction.
Answer: 
Explanation:
Given
mass of wagon m=5 kg
elevation

Sin component of weight will oppose the applied force therefore we can write


The figure shown below illustrates a lever being used to lift a weight W.
The applied force is F.
In order to lift the weight, the minimum applied force is
F*b = W*a
F = (a/b)W
When the ratio a/b < 1, then the applied force is less than the weight.
The principle behind the use of a lever is to keep the ratio a/b small in order to decrease the effort force.
Answer: A
A lever is used to decrease effort force.