Physics homework

I need some help. D: I don’t know what equations to use?

A 1450kg car accelerates uniformly from rest. It reaches 24 m/s in 9.2s. Calculate the force needed to cause this acceleration. [4]

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v = u + at
F = ma

Original post by polsan

I need some help. D: I don’t know what equations to use?

A 1450kg car accelerates uniformly from rest. It reaches 24 m/s in 9.2s. Calculate the force needed to cause this acceleration. [4]

Use SUVAT (v = u + at) to find the acceleration, then use F = ma with the acceleration you just worked out to find the force required.

Reply 3

Wonyo

thank you all! i was probably confused as i dont think i was taught the v = u + at before this homework which is weird, but thank you again!

Reply 4

Rehman Mallah

First you want to use the SUVAT equation

v= u+at

You want to find a so you plug the values in

a = (v-u)/t

Since the car accelerates uniformly ,

u=0m/s

and you are given the other values
After finding the acceleration using SUVAT, just use

F=ma

to find the force required.

(edited 5 years ago)

Reply 5

_Mia101

Study Forum Helper

Original post by TheEpicToaster

Use SUVAT (v = u + at) to find the acceleration, then use F = ma with the acceleration you just worked out to find the force required.

What is SUVAT?

And shouldn't you use a = (v-u)/t

Then use F=ma to find out the force

Reply 6

Guarddyyy

I would assume you are in first year A-levels. You should take a quick look through the 4 (5 if you count the last one I mention) and try to memorise them ASAP and the derivations.

1) v = u + at
2) s = (u+v)/2 * t
3) s = ut + 1/2(at^2)
4) v^2 = u^2 + 2as
5) s = vt - 1/2(at^2)

I'd assume you know what all the symbols mean

Reply 7

TheEpicToaster

Original post by _Mia101

What is SUVAT?

And shouldn't you use a = (v-u)/t

Then use F=ma to find out the force

SUVAT is a commonly used term for the equations of motion. When you rearrange v = u + at, you get a = (v-u)/t, but since the car starts at rest, u = 0, so a = v/t.

Reply 8

_Mia101

Study Forum Helper

Original post by TheEpicToaster

SUVAT is a commonly used term for the equations of motion. When you rearrange v = u + at, you get a = (v-u)/t, but since the car starts at rest, u = 0, so a = v/t.

Oh, okay thanks!

Reply 9

Wonyo

Original post by Guarddyyy

Surprisingly, I’m actually in year 11 lol

Reply 10

TheEpicToaster

Original post by _Mia101

Oh, okay thanks!

You're welcome!

Reply 11

Guarddyyy

Original post by polsan

Surprisingly, I’m actually in year 11 lol

Start learning early :wink:

Reply 12

username2889812

Original post by _Mia101

What is SUVAT?

And shouldn't you use a = (v-u)/t

Then use F=ma to find out the force

s- displacement
u = initial velocity
v= final velocity
a = acceleration
t= time

There's a set of equations used when acceleration is constant ...(I started to learn in AS)
https://www.google.com/imgres?imgurl=https%3A%2F%2Fwww.onlinemathlearning.com%2Fimage-files%2Fsuvat-equations.png&imgrefurl=https%3A%2F%2Fwww.onlinemathlearning.com%2Fkinematics-suvat.html&docid=zoma4MreYdH-ZM&tbnid=BsFgkIksLrjAxM%3A&vet=10ahUKEwjxx_nr34veAhXMDcAKHVWqDcsQMwheKAAwAA..i&w=414&h=347&safe=strict&bih=626&biw=1366&q=suvat%20equations&ved=0ahUKEwjxx_nr34veAhXMDcAKHVWqDcsQMwheKAAwAA&iact=mrc&uact=8

(edited 5 years ago)

Reply 13

Wonyo

I didn’t know about SUVAT but since it’s been explained it’ll be really useful for me, so thank you! :smile:

I actually struggle with physics the most out of biology and chemistry, but I feel like it’s getting easier to handle... 🤔

Reply 14

_Mia101

Study Forum Helper

Original post by Spannerin'moi

Thanks!
Would it be too early to start learning them in year 10?

Reply 15

Wonyo

Original post by _Mia101

Thanks!
Would it be too early to start learning them in year 10?

From a Year 11, I definitely don’t remember this stuff, but if you really want to consolidate learning I think it’s useful to remember outside of your the topic you’re doing currently. I think it’s good practice to go over equations, especially for Physics

Reply 16

Guarddyyy

If you plan to do physics, there's no harm in having a look in the future content. Getting your head around the basic principles is always the best, then you can do a range of questions.