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# M1 suvat watch

1. does mass affect the speed?

''a small object of mass 0.02kg at the top of a building 160m high is dropped from rest''

a) find speed of object as it hits the ground

i think i remember something about mass not affecting speed, so is this question just trying to confuse me
2. (Original post by ihatePE)
does mass affect the speed?

''a small object of mass 0.02kg at the top of a building 160m high is dropped from rest''

a) find speed of object as it hits the ground

i think i remember something about mass not affecting speed, so is this question just trying to confuse me
That's right. If we ignore air resistance, all objects fall at the same rate.
3. (Original post by ihatePE)
does mass affect the speed?

''a small object of mass 0.02kg at the top of a building 160m high is dropped from rest''

a) find speed of object as it hits the ground

i think i remember something about mass not affecting speed, so is this question just trying to confuse me
You don't need the mass for part a).
4. (Original post by Mr M)
That's right. If we ignore air resistance, all objects fall at the same rate.
it does say that. so if we were to have air resistance, does that mean mass will affect speed?
(Original post by NotNotBatman)
You don't need the mass for part a).
okie dokie, thanks
5. (Original post by Mr M)
That's right. If we ignore air resistance, all objects fall at the same rate.
(Original post by NotNotBatman)
You don't need the mass for part a).
oh for part b, it says assuming that air resistance has magnitude 0.096N calculate magnitude of acceleration, do i use f=ma?
6. (Original post by ihatePE)
it does say that. so if we were to have air resistance, does that mean mass will affect speed?
If there is air resistance, speed will not continue to increase for as long as the object is falling. Eventually the weight will equal the air resistance force and the object will fall at constant speed.

https://en.wikipedia.org/wiki/Terminal_velocity
7. (Original post by ihatePE)
oh for part b, it says assuming that air resistance has magnitude 0.096N calculate magnitude of acceleration, do i use f=ma?
You do use F=ma, but not straight away. First you must determine the net force acting downwards on the object. The object's weight is acting downwards while the given air resistance is acting upwards. Once you have the net downwards force, you can use F=ma rearranged as a=F/m.

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