If a person want to move a <span>heavy box across the room, he must apply a force that is greater than starting frictional force acted on the heavy box in order to get the box in motion. the frictional force is equal to coefficient of friction times the normal force, and normal force is approximately the weight of the object. so the force that must be applied must be greater than the wieght of the object.</span>
No, no me habla espanol. yo soy ingles
Answer:
Well I'm going to go with A.
Explanation:
As per the question the mass of the boy is 40 kg.
The boy sits on a chair.
We are asked to calculate the force exerted by the boy on the chair at sea level.
The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.
At sea level the acceleration due to gravity g = 9.8 m/s^2
Therefore, the weight of the boy [m is the mass of the body]
we have m = 40 kg.
Therefore, w = 40 kg ×9.8 m/s^2
=392 N kg m/s^2
= 392 N
392 is not an option but I'm guessing you can round down 2 .to option A. 390...?
Answer:
The time it takes light to cover 1.5 km was too short to be measured by Galileo's instruments.
Explanation:
The speed of light is
, which means the time it takes to cover a distance of 1.5 km (or 1,500m) will be


which is
of a second! This time delay could in no way be measured by Galileo considering the fact that he was using his heartbeat to measure time!
Answer:
True
Explanation:
Because AxB=lAllBlsin(x)
and x is the angle between them
so, the angle is 180° and sin180 is zero.