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Force - Effects of Force

Grade 6ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Force is defined as a push or a pull acting on an object resulting from its interaction with another object. The SI unit of force is the Newton, denoted by NN.

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Force is a vector quantity, which means it has both magnitude and direction. It is often represented by an arrow showing the direction of application.

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Effect 1: Change in State of Motion. A force can move a stationary object (initial velocity u=0u = 0) or stop a moving object.

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Effect 2: Change in Speed. If a force is applied in the direction of motion, the speed increases. If applied in the opposite direction, the speed decreases.

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Effect 3: Change in Direction. A force can change the path of a moving body without necessarily changing its speed, such as a stone whirled in a circle or a car taking a turn.

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Effect 4: Change in Shape and Size. Temporary or permanent deformation can occur when force is applied to an object, such as stretching a rubber band or squeezing a lump of clay.

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The gravitational pull exerted by the Earth on an object is called its weight (WW), which is a specific type of force.

📐Formulae

F=mimesaF = m imes a

W=mimesgW = m imes g

1 kgf≈9.8 N1\text{ kgf} \approx 9.8\text{ N}

Fnet=F1+F2 (Forces in the same direction)F_{net} = F_1 + F_2 \text{ (Forces in the same direction)}

Fnet=F1−F2 (Forces in opposite directions)F_{net} = F_1 - F_2 \text{ (Forces in opposite directions)}

💡Examples

Problem 1:

A wooden block is pushed by two friends, Rahul and Amit. Rahul applies a force of 15 N15\ N towards the right, and Amit applies a force of 10 N10\ N also towards the right. Calculate the resultant force acting on the block.

Solution:

Fnet=15 N+10 N=25 NF_{net} = 15\ N + 10\ N = 25\ N towards the right.

Explanation:

When two forces act in the same direction, their magnitudes are added to find the net force (FnetF_{net}).

Problem 2:

Identify the effect of force when a goalkeeper catches a moving football.

Solution:

The force changes the state of motion from motion to rest.

Explanation:

The goalkeeper applies an opposing force to the ball, reducing its velocity to v=0v = 0.

Problem 3:

If an object has a mass of 5 kg5\ kg, calculate its approximate weight on Earth using g≈10 m/s2g \approx 10\ m/s^2.

Solution:

W=5 kg×10 m/s2=50 NW = 5\ kg \times 10\ m/s^2 = 50\ N.

Explanation:

Weight is the force of gravity acting on a mass, calculated using the formula W=m×gW = m \times g.

Effects of Force - Revision Notes & Key Formulas | ICSE Class 6 Science