Grade 8 - Worksheets - Integrated Science - Free Printable

Here is the complete solution to the worksheet, with clear explanations for each part.

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1. (a) Define the term force and state its SI unit. (2 marks)

> Force is a push or pull acting upon an object as a result of its interaction with another object. It can cause an object to accelerate, decelerate, remain in place, or change shape.
>
> The SI unit of force is the newton (N).
>
> *Explanation:* One newton is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared (1 N = 1 kg·m/s²).

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1. (b) Briefly explain Newton’s first and second law of motion. (4 marks)

> Newton’s First Law (Law of Inertia):
> An object at rest will stay at rest, and an object in motion will continue moving at a constant velocity (same speed and direction), unless acted upon by an unbalanced external force.
>
> *Example:* A book lying on a table stays there until you push it. A hockey puck slides across ice until friction or a stick stops it.
>
> Newton’s Second Law:
> The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This is mathematically expressed as:
> F = ma
> where F is the net force, m is the mass, and a is the acceleration.
>
> *Example:* Pushing a shopping cart lightly gives it small acceleration; pushing harder (more force) gives greater acceleration. A heavier cart (more mass) accelerates less under the same force.

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1. (c) The wind pushes a paper cup along the sand at a beach. The cup has a mass of 0.025 kg and accelerates at a rate of 5 m/s². How much force is the wind exerting on the cup? (3 marks)

> We use Newton’s Second Law:
> F = m × a
>
> Given:
> Mass (m) = 0.025 kg
> Acceleration (a) = 5 m/s²
>
> So,
> F = 0.025 kg × 5 m/s² = 0.125 N
>
> ✔ Answer: The wind exerts a force of 0.125 newtons on the cup.

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2. (a) Describe two ways in which friction helps you on a daily basis. (2 marks)

> 1. Walking or running: Friction between your shoes and the ground prevents slipping. Without friction, you would slide around like on ice.
>
> 2. Driving a car: Friction between the tires and the road allows the car to move forward, stop, and turn safely. Brakes also rely on friction to slow down the wheels.

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2. (b) List two ways in which friction can be reduced. (2 marks)

> 1. Use lubricants: Applying oil, grease, or other lubricants between moving parts reduces friction (e.g., in engines or door hinges).
>
> 2. Use ball bearings or rollers: Replacing sliding friction with rolling friction (e.g., in bicycles or skateboards) significantly reduces resistance.

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3. Match one item of column A to one item of column B. (4 marks)

> Here are the correct matches based on the function of each tool:

| Column A | Column B |
|----------------------------------------|-------------|
| Lift a car so you can change a wheel | A jack |
| Lift a bucket of cement to the top of a building under construction | A pulley |
| Remove a big rock from the ground | A crowbar |
| Drill a hole through a board | An auger |

> *Explanation:*
> - A jack is specifically designed to lift heavy objects like cars.
> - A pulley system is used to lift heavy loads vertically with less effort — perfect for lifting buckets of cement.
> - A crowbar is a lever used to pry or lift heavy objects like rocks.
> - An auger is a type of drill bit or tool designed for boring holes in wood or soil.

✔ All matches are correct.

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Total Marks Breakdown:
- Q1(a): 2 marks
- Q1(b): 4 marks
- Q1(c): 3 marks
- Q2(a): 2 marks
- Q2(b): 2 marks
- Q3: 4 marks
→ Total: 17 marks

Let me know if you’d like this formatted as a printable answer sheet!