What is the mass of this object?

[chengbin]

Homework Statement

A net force of 200N is applied to an object, causing its velocity to change from 30km/h to 20km/h in 2.3s.

Homework Equations

What is the object's acceleration? What is its mass?

The Attempt at a Solution

I got the correct answer for acceleration (-1.2m/s^2), but I'm having trouble with finding the mass.

I'm getting 199kg (m = 200N/1.2m/s^2), but the answer key says 170g. How is that correct?

 

[Rick88]

200/1.2 does not equal 199.

The answer should indeed be about 170kg.
Check your calculations again.

 

[chengbin]

Thanks.

Apparently I can't use my calculator properly.

I guess 170g is probably a typo in the book.

 

[Rick88]

they probably meant 170kg.
I got 167.8kg, which approximated to two significant figures gives indeed 170kg.

 

[rwisz]

As a scientist, the mass of an object is a measure of its inertia, or resistance to changes in motion. It is typically measured in kilograms (kg) or grams (g). In this case, the mass of the object cannot be determined from the given information. While the force and acceleration can be calculated, the mass of the object is not provided. Additionally, the units used in the attempted solution (kg) do not match the units used in the answer key (g). It is important to pay attention to units in scientific calculations, as they can greatly affect the final result. Without knowing the mass of the object, it is not possible to accurately determine its resistance to changes in motion.