Q.A block of mass 2 kg is being brought down by a string. If the block acquires a speed 1 m/s in dropping down 25 cm, find the work done by the string in the process.
A mass of a block is 2 kg which is attached by a string and being bought down . It acquires a speed of 1m/s when the displacement of a block is 25 cm from its initial condition And we need to find the work done by the string in the process .
First to understand the question more nicely let's draw the figure . [ See the attachment - 1 ]
Now we can solve it by using the formula of Newton 2nd law and then by it we need to find the tension and acceleration .
At last in order to find the value of work done we need to apply the formula given below.
☕ Work done :-
Now let's solve it !
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✤ Solution :
↪ Refer to the second attachment...!
By applying the Newton 2nd law we can write that
Net force = m.a
→ 2 × 10 - T = 2 × a [ While taking 10 the value of g ]
Now let's calculate tension of string
★ Tension = 20 - 2a ...(1)
We can see that in order to calculate tension we need to find the acceleration .so ,
★ Acceleration = v² = u² + 2as
Now let's write the value
v ( Final velocity ) = 1
u ( Initial velocity ) = 0 [ initial velocity was in rest therefore it will be zero ]
s ( Displacement ) = 25 cm = 25/100 m
Let's put the value
★ Acceleration = v² = u² + 2as
➙ (1)² = (0)² + 2 × a × 25/100
➙ a = 2m/s²
Now , we know the value of acceleration . so , let's put the value of acceleration in order to find tension
★ Tension = 20 - 2a ...(1)
➙ 20 - 2 × 2
➙ 16 Newton
We know the formula of work done which is ,
we know that force (tension) is in upward direction and displacement is in downward direction .
Answers & Comments
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✤ Required Answer:
✒ GiveN:
✒ To FinD:
Work done by string ?
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✤ How to solve?
A mass of a block is 2 kg which is attached by a string and being bought down . It acquires a speed of 1m/s when the displacement of a block is 25 cm from its initial condition And we need to find the work done by the string in the process .
First to understand the question more nicely let's draw the figure . [ See the attachment - 1 ]
Now we can solve it by using the formula of Newton 2nd law and then by it we need to find the tension and acceleration .
At last in order to find the value of work done we need to apply the formula given below.
☕ Work done :-
Now let's solve it !
━━━━━━━━━━━━━━━━━━━━
✤ Solution :
↪ Refer to the second attachment...!
By applying the Newton 2nd law we can write that
→ 2 × 10 - T = 2 × a [ While taking 10 the value of g ]
Now let's calculate tension of string
★ Tension = 20 - 2a ...(1)
We can see that in order to calculate tension we need to find the acceleration .so ,
★ Acceleration = v² = u² + 2as
Now let's write the value
Let's put the value
★ Acceleration = v² = u² + 2as
➙ (1)² = (0)² + 2 × a × 25/100
➙ a = 2m/s²
Now , we know the value of acceleration . so , let's put the value of acceleration in order to find tension
★ Tension = 20 - 2a ...(1)
➙ 20 - 2 × 2
➙ 16 Newton
We know the formula of work done which is ,
we know that force (tension) is in upward direction and displacement is in downward direction .
Now let's write the value
let's put the value,
☀️ Hence, solved !!
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