# Homework Help: Work done by tension force

1. Apr 9, 2005

### NoHeart

here's the question:
a mass of 100kg is pulled directly upward a distance of 5m by a rope with acceleration 1m/s^2. what is the work done by the tension force?

so the normal force is mg, 100kg*10m/s^2(gravitational constant given)= 1000N
the applied force is 100kg*1m/s^2= 100N
so is the tension 1000+100? if so the work done is 1100N*5m= 5500J
it's being pulled straight up, so the angle is 0, cos0=1

is it correct to add the two forces to find the total tension?

2. Apr 9, 2005

### quasar987

<quasar go hide in the corner>

Last edited: Apr 9, 2005
3. Apr 9, 2005

### xanthym

SOLUTION HINTS:
From problem statement:
{Mass of Object} = m = (100 kg)
{Gravitational Force Downward on Object} = m*g = (100 kg)*(9.81 m/sec^2) = (981 N)
{Acceleration of Object Upwards} = a = (1 m/sec^2)
{Distance Object Pulled Upwards} = H = (5 m)
{Rope Tension Force Upward} = T

{NET Total Force on Object Upward} = m*a =
= {Rope Tension Force Upwards} - {Gravitational Force Downward} =
= T - m*g
::: ⇒ m*a = T - m*g
::: ⇒ T = m*a + m*g

{Work Done By Rope Tension} =
= {Rope Tension Force Upward}*{Distance Object Pulled Upwards} =
= T*H =
= {m*a + m*g}*H

::: ⇒ {Work Done By Rope Tension} = {m*a + m*g}*H
Evaluate above equation to determine work performed by Rope Tension.

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Last edited: Apr 9, 2005