At a county fair weigh-in, a prize pumpkin hangs from a strap. Everyone asks how big it is. Physics asks a different question: how hard is the Earth pulling on it?
That pull has a name you have already met, and from now on it gets a number and a symbol.
You have met the weight force: the Earth's downward pull on an object, acting wherever the object is near Earth. Weight is a force. That one sentence sets everything else.
What is an object's weight?
Because weight is a force, it is measured in newtons, like every force.
Weight is measured in:
The hanging pumpkin's weight is the Earth's downward pull on it, given in newtons.
Weight gets its own symbol: lowercase w.
Which symbol does this course use for weight?
Everyday talk says a pumpkin 'weighs' some number of pounds. In this course, weight means the force: the Earth's pull, in newtons.
So a weight is reported like any force: a magnitude in newtons, and its direction is always straight down.
A dog's weight is 180 N. What exactly does that number measure?
Weight is the gravitational force on an object.
The Earth exerts it, and the newton is the force unit.
The size of the Earth's downward pull on the dog: 180 N.
Name a hanging fern's weight in full: which object exerts it, which object it acts on, and its direction.
Weight is the Earth's pull on the object.
Its direction is straight down.
The Earth exerts it, it acts on the fern, and it points straight down.
Which statement about a watermelon's weight is correct?
Four readings are listed in a field notebook: 250 N, 250 kg, 250 m, 250 s. Which could be a weight?
A hiker's weight is a force. Which pair of objects names it fully?