Welcome :: Homework Help and Answers :: Mathskey.com

Recent Visits

  
Welcome to Mathskey.com Question & Answers Community. Ask any math/science homework question and receive answers from other members of the community.

13,435 questions

17,804 answers

1,438 comments

774,890 users

A Physics question?

0 votes

A 520 g block is suspended by a string that is wrapped around a rotating disk. The block is released from rest and accerlates at 2.1 m/s^2 downward. (a) find the tension in the string. (b) calculate the mas of the disk

asked Nov 6, 2014 in PHYSICS by anonymous

2 Answers

0 votes

(a)

The mass of the block is 520 g = 0.52 kg.

Accerlation = 2.1m/sec²

The tension in the string in moving the object downward T = mg - ma.

Garvitational Force Fg

Fg = mg

Fg = 0.52 * 9.8

Fg = 5.096 N

We know that force F = ma

F = 0.52*2.1

F = 1.092 N

Then Tension in the String

T = mg - ma

T = 5.096 - 1.092

T = 4.004 N.

Tension in the string is 4.004 N.

answered Nov 6, 2014 by dozey Mentor
edited Nov 6, 2014 by dozey
0 votes

(b)

The mass of the block is 520 g = 0.52 kg.

Accerlation = 2.1m/sec²

The tension in the string in moving the object downward T = mg - ma.

Garvitational Force Fg

Fg = mg

Fg = 0.52 * 9.8

Fg = 5.096 N

We know that force F = ma

F = 0.52*2.1

F = 1.092 N

Then Tension in the String

T = mg - ma

T = 5.096 - 1.092

T = 4.004 N.

Now the Torque in the solid disk

Torque = T*r where T is the tension in the string.

We also know that

Torque  = I * α.

Where I is the moment of inertia = (1/2) mr².

And α = a/r

Torque  = (1/2) Mr² * (a / r).

Torque  = (1/2) M * a * r.

T * r = (1/2) M * a * r

T = (1/2) M * a

M = 2T / a

M = (2 * 4.004) / 2.1

M = 3.81 kg.

Therefore the mass of the Disk is 3.81 kg.

answered Nov 6, 2014 by dozey Mentor
edited Nov 6, 2014 by bradely

Related questions

asked Nov 20, 2014 in PHYSICS by anonymous
asked Oct 28, 2014 in PHYSICS by anonymous
...