Question

please solve this question and answer Std: 9th
subject: science
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Answer 1

Question 1st. Which would require a greater force: accelerating a 8 kg mass at 10 m/s sq. or a 3 kg mass at 3 m/s sq.!?

Answer 1st.

Provided that:

★ Condition number first!

• Mass = 8 kg
• Acceleration = 10 m/s sq.

★ Condition number second!

• Mass = 3 kg
• Acceleration = 3 m/s sq.

To determine:

• Greater force required by which body!?

Solution:

• Greater force is required by body second that is in condition second.

Using concept:

• Second law of motion that tell us about force formula.

Using formula:

• F = ma

Where, a denotes acceleration, F denotes force and m denotes mass.

Required solution:

† Firstly let us calculate the force in condition number first!

»»» F = ma

»»» F = 8(10)

»»» F = 80 N

»»» Force = 80 Newton

† Now let us calculate the force in condition number second!

»»» F = ma

»»» F = 3(3)

»»» F = 9 N

»»» Force = 9 Newton

† Which one require more force!?

»»» Force = 80 N > Force = 9 N

»»» Condition first > Condition second

»»» Therefore, object in condition second need more force!

____________________________

Question 2nd. An object of mass 500 kg is accelerated from velocity of 3 mps to 7 mps in 20 seconds. Calculate initial and final momentum. Also find force!

Answer 2nd.

Provided that:

• Mass = 500 kg
• Initial velocity = 3 mps
• Final velocity = 7 mps
• Time = 20 seconds

To calculate:

• The initial momentum
• The final momentum
• The force

Solution:

• The initial momentum = 1500 kg m/s

• The final momentum = 3500 kg m/s

• The force = 100 Newton

Using concepts:

• Initial momentum formula
• Final momentum formula
• Force formula

Using formulas:

• Initial momentum formula:

• p = mu

• Final momentum formula:

• p′ = mv

• Force formula:

• F = m(v-u)/t

Where, p denotes initial momentum, p′ denotes final momentum, m denotes mass, v denotes final velocity, u denotes initial velocity and t denotes time.

Required solution:

~ Firstly let us calculate the initial momentum by using suitable formula!

»»» p = mu

»»» p = 500(3)

»»» p = 1500 kg m/s

»»» Initial momentum = 1500 kg m/s

~ Now let us calculate the final momentum by using suitable formula!

»»» p′ = mv

»»» p′ = 500(7)

»»» p′ = 3500 kg m/s

»»» Final momentum = 3500 kg m/s

~ Now let's calculate the force!

»»» F = m(v-u)/t

»»» F = 500(7-3)/20

»»» F = 500(4)/20

»»» F = 2000/20

»»» F = 200/2

»»» F = 100 N

»»» Force = 100 Newton $\:$