Let's first imagine the man pushing on a car with the handbrake on. Obviously, the car does not move. The man is applying a force F (let us call it F1). The static friction of the brakes on the car are applying a force we shall call F2.
Now, we know from Newton's laws that F = mass x acceleration (F = ma). The car is not accelerating, so F = 0. That is the net force of the man/car system is zero. So, F1 + F2 = 0, or if you prefer, F1 = -F2.
In this case, the force of the man's feet on the ground cannot overcome the force of the brakes on the wheels. So the car does not move.
Now, what happens if we release the handbrake? If enough force is applied to overcome the friction of the wheels and axles etc, the car will accelerate (a).
The man's feet exert a force on the ground and the ground exerts an equal and opposite for on the man's feet. (Newton's 3rd law)
The friction of the wheels exerts a force on the ground and the ground exerts an equal and opposite force on the wheels. (Newton's 3rd law)
The man exerts a force on the car... and the car exerts an equal and opposite force on the man (3rd law)
But, the force of the man's feet on the ground is greater than the opposing force of the wheel's friction on the ground. Therefore, there is a net force and the "man + car" system accelerates. Note that Newton's 3rd law applies to each pair of objects (car/ground), (car/man), (man/ground) seperately.
The reaction force to a man pushing on a car is the force exerted by the car on the man in the opposite direction. According to Newton's third law of motion, for every action, there is an equal and opposite reaction.
pushing a pram kicking a ball pushing the door pushing the car
The equal and opposite force to the downward force of gravity pulling on a man standing on the beach is the normal force exerted by the ground pushing back up on the man. This normal force prevents the man from sinking into the ground due to the force of gravity.
The wall exerts a reaction force of 50 N on the man, equal in magnitude but opposite in direction to the force that the man exerts on the wall.
The force applied by the man pushing the box is balanced by the force of friction between the box and the floor. This results in a net force of zero, leading to the box moving with constant velocity.
The reaction force to a man pushing on a car is the force exerted by the car on the man in the opposite direction. According to Newton's third law of motion, for every action, there is an equal and opposite reaction.
pushing a pram kicking a ball pushing the door pushing the car
You can't find the force from that data. The TOTAL force must be zero if there is no acceleration - but any force provided by the man, pushing against the wall, is counteracted by the Earth pushing back.
The man exerts a force of 600 N and the woman exerts a force of 300 N. Work done by the man = Force x displacement = 600 x 20 = 12,000 J Hence, the man performs 12,000 joules of work.
The action is the man exerting an upward force on the bucket to hold it up. The reaction is the bucket exerting an equal and opposite downward force on the man's hand.
The equal and opposite force to the downward force of gravity pulling on a man standing on the beach is the normal force exerted by the ground pushing back up on the man. This normal force prevents the man from sinking into the ground due to the force of gravity.
The wall exerts a reaction force of 50 N on the man, equal in magnitude but opposite in direction to the force that the man exerts on the wall.
The net force of the man and Fred on the crate is 20 Newtons. This is because force is additive, so the two forces of 10 Newtons each combine to create a total force of 20 Newtons acting on the crate in the direction of the push.
The force applied by the man pushing the box is balanced by the force of friction between the box and the floor. This results in a net force of zero, leading to the box moving with constant velocity.
The work done by the man is 1500 Joules. This is calculated by multiplying the force (150 N) by the distance the box was pushed (10 m). Work is the product of force and distance, in this case, the man exerted a force of 150 N to move the box 10 m across the room.
The reaction force is the push of the ball on the Earth, according to Newton's third law of motion. This means as the Earth pulls the ball downward, the ball also exerts an equal and opposite force back up on the Earth.
The force of gravity pulls the man toward the ground, creating contact between his feet and the surface. This contact provides the friction needed to push off and move forward while walking.