Force and Time in Collisions
Problems of this nature usually consider two equations:
I=Ft and;
I=\Delta P=mv-mu
Example 1:
A 20N force acts on a stationary RC car of mass 2.5kg for 3.0s
a) Calculate the magnitude of the impulse of the force on the car:
b) Calculate the change in speed the impulse produces:
a) I=Ft
I=20\times 3=60Ns
b) Impulse = \Delta p, and \Delta p=mv-mu=m(v-u)
Therefore; 60=2.5(v-0)
v=\cfrac { 60 }{ 2.5 }
v=24\cfrac { m }{ s }
Example 2:
A toy car of mass 2kg is at rest. A force acts on it for 4.0s, increasing its speed to 8\cfrac { m }{ s }
a) Find the impulse the force applies:
I=\Delta p=mv-mu
I=\Delta p=(2\times 8)-(2\times 0)
I=16Ns
b) Find the force applied to the car.
I=Ft
16=F\times 4
F=\cfrac { 16 }{ 4 }
F=4N