a 750 g toy car is running at 2.5 m/s. what is the force must be applied for 4 seconds so that its velocity wi

Question

plz include the given and the formula?
our topic is about law of motion

tnx

Answer 1

As you haven't given the final velocity I assume you want it to be 0m/s
The initial momentum of toy car(p1)=m*u
Where m is the mass of the car and u is the initial velocity
Here m=750 g=750/1000 kg=.75 kg(because the units taken should be in S.I unit)
u=2.5
So p1=.75*2.5=1.875 kgm/s
The final momentum p2=m*v
Here v= 0m/s(I assumed)
So the final momentum p2=0 kgm/s
We difine force as The change of momentum by time.
So force(f)=(p2-p1)/t
Here p2=0 p1=1.875 t=4
So f=(0-1.875)/4
f=(-1.875)/4
f=-0.46875 N

So the force required to change the velocity of car from 2.5 to 0m/s in 4 s is -0.46875 N

Another way to do is to find the accelaration is to find the accelaration accelaration is given by the equation
a=v-u/t
Where v is final velocity u is initial velocity t is time
After that multiply accelaration by the mass of object.
because f=m*a
You will have the force


If the final velocity is different then follow the steps which I showed you.

Hope that helped

Answer 2

From Newton's Laws, F=ma. If you want to know the force necessary to cause a change in velocity (i.e. acceleration) just use this formula. The mass in your example is .750 kg (must use kilograms to get force in Newtons). For velocity to change from 2.5 m/s to x m/s in time t, the acceleration is a=(v.final - v.initial)/t. If your question is about reducing velocity to 0, answer is:

a = (0-2.5 m/s)/4 s = -2.5/4 = -.625 m/s2
F=ma = .750kg*(-.625 m/s2) = -0.46875 kg-m/s2

However, since you have only 2 significant figures in your time measurement, we must round to -0.47 kg-m/s2.

A kg-m/s2 is the unit of force, called a Newton (N), so the final answer is:

F = -0.47N

Note that the force has a minus sign in front of it, since the force acts in the direction opposite to the velocity in order to slow (decelerate) it to 0. Remember, in general, these are all vector quantities, so direction is important!

Answer 3

Your question isn't complete, but what you need to know is the formula

∆v = a*∆t

∆v = velocity change, a = acceleration.

then a = ∆v/∆t; divide the velocity change by ∆t (4 sec) to get a

then F= m*a (Newton's law of motion.)