Question

I'm having trouble figuring out how to figure for these answers. :/ some help, please?
What would be the weight of the following items in the chemistry lab? Round to the nearest tenth.
2.5 kg of lead = 24.5 newtons
0.7 kg of gold = 6.9 newtons
430 g of copper = 4.2 newtons
2570 ml of water = 25.2 newtons

Answer 1

It relevant that w = g * m , where w is the weight (in newton) of the object, m the mass of the object, and g ("little gee") is the local gravitationnal value (Almost 10 on earth). You may alos need the density of some of these item.

Answer 2

so it would be in this instance the weight divided by the mass?

Answer 3

No. What you usually use in chemistry is the mass m (of unit: kg or g). Thus for the 3 first, you have the answer without calculation. However for the last one you have to apply the equation I given in this form : m = w/g, and thus m = 25.2/g = 2.5270. (Remark : You may also know that 1 liter of water is one kilogram, and deduce the mass of 2570 ml of water.)

Answer 4

how do I have an answer without a calculation?

Answer 5

"2.5 kg of lead = 24.5 newtons" : it says "2.5 kg of lead", so you would have, in a lab or elsewhere, a mass of 2.5 kg of lead. No calculation required.

Answer 6

but I need to know how to find 24.5 N :/

Answer 7

As told before, w = m * g
w is the weight in newton ( for example, 24.5N is a weight).
m is the mass, in kilogram or gram (eg, 2.45 kg)
g is a constant on earth, its value is around 10 (More accuralety : 9.81).

If you want to find the weight 24.5N, you have to solve w = m * g. Is that clear ?

Answer 8

yes thank you :)