Saturday

August 23, 2014

August 23, 2014

Posted by **Benji** on Thursday, November 16, 2006 at 5:33pm.

a) is 3 m/s

b) is 2.65 kg

I don't get the equations I should have used

Use Newton's second law:

F = m a

The tension of 18 N pulls on the 6 kg block, so it's acceleration is:

a = 18 N/(6 kg) = 3 m/s^2

Now the length of the rope can't change and it is pulled tight by the falling weight. This means that if the mass on the surface is accelerating at 3 m/s^2, the mass m is dropping downward with this acceleration.

The force on the hanging rope is (let's take the downward directon as positive):

F = m g - 18 N

But this has to equal m*a by Newton's second law and we know that a = 3 m/s^2.

m g - 18 N = m*(3 meters/s^2) --->

m = 18 N/[g - 3 m/s^2] = 2.64 kg

**Related Questions**

physics - A light rope is attached to a block with a mass of 6 kg that rests on ...

physics - A block of mass M = 6.755 kg is pulled along a horizontal frictionless...

physics - A monkey of mass m climbs a rope slung over a light frictionless ...

Physics - A 10N block is attached to the wall by a rope on a frictionless ...

Physics - A 1.7kg block and a 2.7kg block are attached to opposite ends of a ...

Physics. - A 500 g block lies on a horizontal tabletop. The coefficient of ...

Physics - A 90.0 kg block and a 40.0 kg block are connected by a rope that ...

physics - Block A, with a mass of 50 kg, rests on a horizontal table top. The ...

Physics - A 10 kg block rests on a frictionless table and is whirled in a circle...

Physics - A 100kg mass is connected to a 200kg mass by a massless rope. The two ...