b) The reading shown by one of the above devices is always the same in different places of
earth's surface.
Name the device?
Justify your answer
c)What is the weight of an object of mass 50 kg on Earth and on the Moon?
(Value of g on Earth 9.8 m/s, value of 'g' on moon = 1.62 m/s2)
Weight in earth
Weight in moon
Answers
Answer:
Mass and weight are often used interchangeably in everyday conversation. For example, our medical records often show our weight in kilograms but never in the correct units of newtons. In physics, however, there is an important distinction. Weight is the pull of Earth on an object. It depends on the distance from the center of Earth. Unlike weight, mass does not vary with location. The mass of an object is the same on Earth, in orbit, or on the surface of the Moon.
Units of Force
The equation
F
net
=
m
a
is used to define net force in terms of mass, length, and time. As explained earlier, the SI unit of force is the newton. Since
F
net
=
m
a
,
1
N
=
1
kg
⋅
m/s
2
.
Although almost the entire world uses the newton for the unit of force, in the United States, the most familiar unit of force is the pound (lb), where 1 N = 0.225 lb. Thus, a 225-lb person weighs 1000 N.
Weight and Gravitational Force
When an object is dropped, it accelerates toward the center of Earth. Newton’s second law says that a net force on an object is responsible for its acceleration. If air resistance is negligible, the net force on a falling object is the gravitational force, commonly called its weight
→
w
, or its force due to gravity acting on an object of mass m. Weight can be denoted as a vector because it has a direction; down is, by definition, the direction of gravity, and hence, weight is a downward force. The magnitude of weight is denoted as w. Galileo was instrumental in showing that, in the absence of air resistance, all objects fall with the same acceleration g. Using Galileo’s result and Newton’s second law, we can derive an equation for weight.