Before going to answer this question first we have to understand Newton's third law.
As per newtons third law ,for every action,there is an equal and opposite reaction.The force exerted by a body on other body is called action and force that the body gets in turn is called reaction. They will always act on two different bodies and their direction will be opposite to each other.
As per the question a object is falling under gravity. We are asked to find out the action and reaction forces.
We know that every object having mass will imparts gravitational forces on each other.In this question the earth will apply the force of gravity on the body which is in vertically downward direction.Due to this gravity,the body will fall towards earth with an acceleration of 9.8 m/s^2 .This is the force of action.
The falling object also applies same amount of force on earth in vertically upward direction.But we will not notice any acceleration of earth.It is so because the earth is very massive, so the acceleration produced by earth is very small.The force exerted by the falling object on earth is the force of reaction.
Answer:a
Explanation:
We have to lift the load two loads up one story, so energy required is
let m be the mass of each load and h is the height of each story
Energy 
Here energy gained is the potential energy which depends upon the datum(floor).
For lifting one load up one story
Energy required
thus 
is half of 
So option a is correct
Answer:
the statements the correct one is A
Explanation:
Let's analyze this exercise, vehicles have the same mass and speed, so we can use the momentum impulse ratio
I = ∫ F dt = Δp
the Δp is the same for both cars since they have the same mass and the same speeds, so the momentum is the same in both vehicles
When they indicate that vehicle A was reduced more than vehicle B, this implies that the force acted for a longer time, to have the largest reduction in size, therefore the impact force was less in car A than in car B
Resisting the statements the correct one is A
Answer:
Explanation:
Acceleration is equal to the change in velocity over the change in time, or
where the change in velocity is final velocity minus initial velocity. Filling in:
Note that I made the backward velocity negative so the forward velocity in our answer will be positive.
Simplifying that gives us:
and then isolating the final velocity, our unknown:
3.0(6.0) = v + 3.0 and
3.0(6.0) - 3.0 = v and
18 - 3.0 = v so
15 m/s = v and because this answer is positive, that means that the car is no longer rolling backwards (which was negative) but is now moving forward.
