Question

A child's sled, initially at rest, is pushed while on ice with a constant horizontal force of 20.0 N. The total mass of sled plus cargo is 20.0 kg. How fast is the sled moving after 2.00 s of being pushed? Ignore friction.

A) 1.00 m/s
B) 2.00 m/s
C) 9.80 m/s
D) 20.0 m/s

Answer 1

F=ma
20N/20kg=a

Answer 2

so A is the answer? @Azureilai

Answer 3

No it isnt

Answer 4

but it should be, it is only asking about applied force

Answer 5

It's asking about final velocity

Answer 6

Which is why it has a time component included

Answer 7

@KeithAfasCalcLover so how do i find the answer for this?

Answer 8

Ill write it out for ya :)

Answer 9

So we know that:
\[\eqalign{
&F=20.0N \\
&m=20.0kg \\
&v_i=0m/s \\
&\Delta t=2.00s
}\]
So then we know that:
\[F=ma\rightarrow a=\frac{F}{m}\]
We also know that:
\[a=\frac{\Delta v}{\Delta t}=\frac{v_f-v_i}{\Delta t}\rightarrow v_f=a\Delta t+v_i\]
Since we know \(a=\frac{F}{m}\), we can substitute:
\[v_f=\left(\frac{F}{m}\right)\Delta t+v_i\]
And we obtain:
\[v_f=\frac{F\Delta t}{m}+v_i\]
We can plug in what we know:
\[v_f=\frac{20.0(2.00)}{20.0}+0=\frac{40.0}{20.0}=2.00m/s\]
In conclusion, Since \(B.\phantom{..}2.00m/s\), therefore, the answer is B

Answer 10

Oh ok, I see what you are talking about.