# Rope attached to wall and car

1. Aug 13, 2015

### John_tawil

1. The problem statement, all variables and given/known data
A rope is attached to a wall on one end and to a car on the other end. Someone pushes up on the rope and the car starts to move when the rope makes an angle of 5o with the floor. Mcar=2500kg

2. Relevant equations
ΣFx=ma
ΣFy=ma

3. The attempt at a solution
Look at the car and the rope separately.

I'm assuming the car has;
ΣFx=ma
ΣFy= 0
and the rope has the opposite;
ΣFx= 0
ΣFy= ma

But I'm not getting anywhere? Am I doing it right?

2. Aug 13, 2015

### sophiecentaur

You seems to be mixing up your x and y directions. (And so was i, because I was trying to read the printing laying on its side.)
The only force on the car that's accelerating it is horizontal. The trig will tell you what it is at 5o.
But I don't see how there would be any lower limit to the force needed if there is no friction.

3. Aug 13, 2015

### Staff: Mentor

Nothing is accelerating here. (Not yet, anyway.)

Start by identifying the forces acting on the truck.

4. Aug 13, 2015

### Staff: Mentor

Oops... I didn't notice that it said no friction. (Missed that when trying to read sideways.)

I don't get the point of the problem. With no friction, you need not be a muscleman to move the truck. A fly could do it.

5. Aug 13, 2015

### sophiecentaur

A touch of the "badly written questions' disease, I think.

6. Aug 13, 2015

### John_tawil

So would you need 1N of force up to push to the left?

7. Aug 13, 2015

### sophiecentaur

If there's no friction, 1microNewton would produce finite acceleration. The question appears to be flawed - or it's angled to make you spot the nonsense aspect of it.

8. Aug 13, 2015

Indeed.