Answer:
(d) all of the above
Explanation:
before cutting the screw threads the operator should lubricate all of the machine parts given in the option that is lead screw and gearbox , the ways and the cross slide and the carriage and half-nuts. we should use lubrication because it reduces the overall system friction and if friction is reduced then heat generated due to friction is also decreases which is beneficial
so option (D) will be correct because we need lubricate in all the given parts
Its safe because it isn't something with electricity
Answer:
The correct answer is option 'c':Convection.
Explanation:
When we ignite a campfire the heat produced by combustion heats the air above the fire. As we know that if a gases gains heat it expands thus it's density decreases and hence it rises, if we hold our hands directly above the fire this rising hot air comes in contact with our hands thus warming them.
The situation is different if we are at some distance from the campfire laterally. Since the rising air cannot move laterally the only means the heat of the fire reaches our body is radiation.
But in the given situation the correct answer is convection.
Yes it does have a large spot
The answer is
The force acting on the handles of a plastic shopping bag that is full of groceries are gravitational force, muscular force.
Gravitational force works downwards, and muscular force is applied by the hands lifting bucket upwards. Two forces are in the opposite direction and hence balancing each other. As a result net force is zero.
Learn more things about gravitational and muscular force
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