Aperson of mass 80 kg stands on earth's surface. what is his weight?

89 n

480 n

784 n

980 n

784N

Explanation:

Yo need to multiply the mass of the person by th Earth's gravity, which we know is 9.8m/s²

80kg*9.8m/s² = 784N

The weight of the person on the Earth's surface is 784N

Solution:

The weight and mass are separate things. The weight of the person includes the gravitational acceleration along with the mass of the person as per Newton’s second law.  

So,

Here the mass = 80 kg

We know the gravitational acceleration =

So the weight of the person =

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.