A 4 kg object is pushed with a force of 20 N over a distance of 3 m. If the obje

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Question: A 4 kg object is pushed with a force of 20 N over a distance of 3 m. If the object starts from rest, what is its final speed?

Options:

Correct Answer: 4 m/s

Solution:

Work done = Force × Distance = 20 N × 3 m = 60 J. K.E = 0.5 × m × v², 60 J = 0.5 × 4 kg × v², v = 3.87 m/s.

A 4 kg object is pushed with a force of 20 N over a distance of 3 m. If the object starts from rest, what is its final speed?

A 4 kg object is pushed with a force of 20 N over a distance of 3 m. If the object starts from rest, what is its final speed?

Correct Answer: 3.87 m/s

Step 1: Identify the given values. The mass of the object (m) is 4 kg, the force applied (F) is 20 N, and the distance moved (d) is 3 m.
Step 2: Calculate the work done (W) using the formula: Work done = Force × Distance. So, W = 20 N × 3 m.
Step 3: Perform the multiplication: W = 60 J (Joules).
Step 4: Use the work-energy principle, which states that the work done on the object is equal to its change in kinetic energy (K.E).
Step 5: The formula for kinetic energy is K.E = 0.5 × m × v², where v is the final speed.
Step 6: Set the work done equal to the kinetic energy: 60 J = 0.5 × 4 kg × v².
Step 7: Simplify the equation: 60 J = 2 kg × v².
Step 8: Divide both sides by 2 kg to isolate v²: 30 = v².
Step 9: Take the square root of both sides to find v: v = √30.
Step 10: Calculate the square root: v ≈ 5.48 m/s.

Work-Energy Principle – The work done on an object is equal to the change in its kinetic energy.
Kinetic Energy Formula – Kinetic energy is calculated using the formula KE = 0.5 × m × v².
Newton's Second Law – The relationship between force, mass, and acceleration (F = m × a) is fundamental in understanding motion.