Worksheet Solutions: Force | Physics Class 10 ICSE PDF Download

A. Multiple Choice Questions

Q1. Which of the following is a non-contact force?
(a) Frictional force
(b) Magnetic force
(c) Tension force
(d) Normal reaction
Ans: (b) Magnetic force
Sol: Magnetic force acts without contact; others are contact forces.

Q2. The SI unit of force is:
(a) Dyne
(b) Kilogram
(c) Newton
(d) Joule
Ans: (c) Newton
Sol: 1 Newton = 1 kg × 1 m/s².

Q3. Which of these is always attractive in nature?
(a) Gravitational force
(b) Magnetic force
(c) Electrostatic force
(d) Frictional force
Ans: (a) Gravitational force
Sol: Gravity always pulls objects together.

Q4. When you walk on the ground, which force prevents slipping?
(a) Tension
(b) Friction
(c) Magnetic
(d) Normal
Ans: (b) Friction
Sol: Friction opposes sliding and helps grip the ground.

Q5. Which law explains why a gun recoils when fired?
(a) Newton’s First Law
(b) Newton’s Second Law
(c) Newton’s Third Law
(d) Law of Gravitation
Ans: (c) Newton’s Third Law
Sol: Action–reaction pairs cause the recoil.

B. Short Answer Questions

Q6. Define friction. Give one daily life example.
Ans: Friction is the opposing force that acts between two surfaces in contact, resisting relative motion.
Example: Bicycle brakes work due to friction between the brake pads and the wheel, which slows down and stops the bicycle.

Q7. Why does a body not fall through the floor even though Earth pulls it downward?
Ans: The Earth pulls the body downward due to gravity. The floor pushes upward with an equal and opposite normal reaction force. Since these forces balance each other, the body remains at rest on the floor.

Q8. A ball of mass 2 kg moves with velocity 3 m/s. Find its momentum.
Ans: Momentum = 6 kg·m/s
Sol: Momentum (p) = Mass (m) × Velocity (v).
Here, m = 2 kg, v = 3 m/s.
p = 2 × 3 = 6 kg·m/s.
Momentum represents how difficult it is to stop a moving object.

Q9. What is the difference between centripetal and centrifugal force?
Ans:

• Centripetal Force: A real force that acts towards the center of a circular path. Example: A string provides centripetal force when a stone is whirled in a circle.

• Centrifugal Force: A fictitious or apparent force that seems to push a body outward while moving in a circle. Example: Passengers feel pushed outward when a car takes a sharp turn.

Q10. Why is it easier to open a door by pushing at its handle than near its hinges?
Ans: The turning effect of a force is called torque. Torque = Force × perpendicular distance from the hinge.
At the handle, the distance from the hinge is maximum, so torque is larger, making it easier to open. Near the hinges, the distance is very small, so torque is smaller, and it is harder to open.

C.  Long Answer Questions

Q11. Explain with examples how Newton’s First Law shows the role of inertia.
Sol:

• Law: A body remains at rest or in uniform motion unless acted upon by an external force.

• Inertia: The natural tendency of an object to resist any change in its state.

• Examples:

  1. A book stays at rest on a table until someone pushes it.

  2. Passengers fall forward when a moving bus stops suddenly because their bodies tend to remain in motion.

  3. A rolling ball eventually stops because friction acts as an external force.
     Thus, Newton’s First Law illustrates the property of inertia.

Q12.  A uniform beam is balanced on a pivot. A 10 N weight hangs 3 m to the left, and a 15 N weight hangs 2 m to the right. Is the beam balanced? Show with calculations.
Sol:

• Principle: For balance, anticlockwise moments = clockwise moments.

• Anticlockwise Moment = 10 N × 3 m = 30 Nm.

• Clockwise Moment = 15 N × 2 m = 30 Nm.

• Since both are equal, the beam is in equilibrium and balanced.

Q13.  A force of 20 N acts on a body of mass 5 kg. Find its acceleration. If the force is doubled, what will be the new acceleration?
Sol:

• Formula: F = m × a → a = F ÷ m

• Given: F = 20 N, m = 5 kg
  a = 20 ÷ 5 = 4 m/s²

• If force is doubled, F = 40 N → a = 40 ÷ 5 = 8 m/s²

• Hence, when force doubles on the same mass, acceleration also doubles.

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