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All questions of Forces for Class 8 Exam
What is the standard unit for measuring speed in scientific contexts?- a)Miles per hour (mph)
- b)Kilometres per hour (km/h)
- c)Metres per second (m/s)
- d)Knots
Correct answer is option 'C'. Can you explain this answer?
What is the standard unit for measuring speed in scientific contexts?
a)
Miles per hour (mph)
b)
Kilometres per hour (km/h)
c)
Metres per second (m/s)
d)
Knots
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Tutorpedia Coaching answered |
Scientists use metres per second (m/s) as the standard unit for speed globally, as it aligns with the metric system. Miles per hour, kilometres per hour, and knots are used in specific contexts (e.g., road travel, aviation), but they are not the standard scientific unit, making options A, B, and D incorrect.
How does a tennis ball change direction when hit by a racket?- a)The racket exerts an unbalanced force on the ball
- b)The ball’s weight overcomes air resistance
- c)The ball’s speed remains constant
- d)The forces on the ball become balanced
Correct answer is option 'A'. Can you explain this answer?
How does a tennis ball change direction when hit by a racket?
a)
The racket exerts an unbalanced force on the ball
b)
The ball’s weight overcomes air resistance
c)
The ball’s speed remains constant
d)
The forces on the ball become balanced
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Tutorpedia Coaching answered |
The change in direction occurs because the racket applies a greater force than the ball’s momentum, creating an unbalanced force that alters its path. The ball’s weight and air resistance are not primary factors, speed changes, and forces are unbalanced during the hit, making options B, C, and D incorrect.
What is the unit of measurement for the moment of a force?- a)Newton (N)
- b)Metre (m)
- c)Newton metre (Nm)
- d)Newton per metre (N/m)
Correct answer is option 'C'. Can you explain this answer?
What is the unit of measurement for the moment of a force?
a)
Newton (N)
b)
Metre (m)
c)
Newton metre (Nm)
d)
Newton per metre (N/m)
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Tutorpedia Coaching answered |
The moment of a force is calculated as Moment = Force (in newtons) × Distance (in metres), resulting in the unit newton metre (Nm). Newton is a unit of force, metre is a unit of distance, and newton per metre is not used for moments, making options A, B, and D incorrect.
What happens to an object when the forces acting on it are balanced?- a)It accelerates
- b)It changes direction
- c)It remains at rest or moves at constant speed
- d)It slows down
Correct answer is option 'C'. Can you explain this answer?
What happens to an object when the forces acting on it are balanced?
a)
It accelerates
b)
It changes direction
c)
It remains at rest or moves at constant speed
d)
It slows down
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Tutorpedia Coaching answered |
Balanced forces are equal in size and opposite in direction, resulting in a net force of zero. According to Newton’s First Law, an object with no net force will either remain at rest or continue moving at a constant speed in a straight line. Options A, B, and D describe scenarios with unbalanced forces.
How does a sharp knife increase pressure when cutting?- a)By increasing the force applied
- b)By reducing the contact area
- c)By increasing the contact area
- d)By reducing the force applied
Correct answer is option 'B'. Can you explain this answer?
How does a sharp knife increase pressure when cutting?
a)
By increasing the force applied
b)
By reducing the contact area
c)
By increasing the contact area
d)
By reducing the force applied
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Tutorpedia Coaching answered |
Pressure is calculated as Pressure = Force ÷ Area. A sharp knife has a smaller contact area, which increases pressure for the same force, making cutting easier. Increasing force also raises pressure but is not the primary role of sharpness, and increasing area reduces pressure, making options A, C, and D incorrect.
A car travels 200 metres in 40 seconds. What is its speed?- a)5 m/s
- b)8 m/s
- c)10 m/s
- d)2 m/s
Correct answer is option 'A'. Can you explain this answer?
A car travels 200 metres in 40 seconds. What is its speed?
a)
5 m/s
b)
8 m/s
c)
10 m/s
d)
2 m/s
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Keystone Instructors answered |
Speed is calculated as Speed = Distance ÷ Time. Here, 200 metres ÷ 40 seconds = 5 m/s. Option B (200 ÷ 25 = 8), option C (200 ÷ 20 = 10), and option D (200 ÷ 100 = 2) result from incorrect calculations or assumptions.
What factor increases the rate of diffusion in gases?- a)Lower temperature
- b)Smaller concentration difference
- c)Higher temperature
- d)Reduced particle movement
Correct answer is option 'C'. Can you explain this answer?
What factor increases the rate of diffusion in gases?
a)
Lower temperature
b)
Smaller concentration difference
c)
Higher temperature
d)
Reduced particle movement
|
Rahul Kumar answered |
Higher temperatures increase the speed of gas particles, accelerating diffusion as particles move faster from areas of high to low concentration. Lower temperatures slow diffusion, smaller concentration differences reduce the rate, and reduced particle movement is not a factor, making options A, B, and D incorrect.
Why is the base of a dam wider than the top?- a)To reduce water flow
- b)To balance the dam’s weight
- c)To increase atmospheric pressure
- d)To withstand higher pressure at greater depth
Correct answer is option 'D'. Can you explain this answer?
Why is the base of a dam wider than the top?
a)
To reduce water flow
b)
To balance the dam’s weight
c)
To increase atmospheric pressure
d)
To withstand higher pressure at greater depth
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Rahul Kumar answered |
Pressure in liquids increases with depth due to the weight of the liquid above. The dam’s base is wider to provide greater structural strength to resist the higher water pressure at the bottom. It does not reduce flow, affect atmospheric pressure, or balance weight in this context, making options A, C, and B incorrect.
What does a horizontal line on a distance-time graph represent?- a)Constant speed
- b)Increasing speed
- c)Stationary object
- d)Decreasing speed
Correct answer is option 'C'. Can you explain this answer?
What does a horizontal line on a distance-time graph represent?
a)
Constant speed
b)
Increasing speed
c)
Stationary object
d)
Decreasing speed
|
Subset Academy answered |
A horizontal line on a distance-time graph indicates that the distance remains constant while time progresses, meaning the object is stationary (speed = 0). A straight upward line represents constant speed, a curved line may indicate changing speed, and a downward line shows movement back toward the starting point, making options A, B, and D incorrect.
What causes a falling object with a parachute to reach terminal velocity?- a)The parachute increases the object’s weight
- b)Air resistance becomes equal to the object’s weight
- c)The parachute reduces atmospheric pressure
- d)The object’s speed increases indefinitely
Correct answer is option 'B'. Can you explain this answer?
What causes a falling object with a parachute to reach terminal velocity?
a)
The parachute increases the object’s weight
b)
Air resistance becomes equal to the object’s weight
c)
The parachute reduces atmospheric pressure
d)
The object’s speed increases indefinitely
|
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Tutorpedia Coaching answered |
Terminal velocity occurs when the upward air resistance equals the downward weight of the falling object, balancing the forces. This results in a constant speed with no further acceleration. The parachute does not increase weight, reduce atmospheric pressure, or cause indefinite speed increase, making options A, C, and D incorrect.
Chapter doubts & questions for Forces - Year 8 Science IGCSE (Cambridge) 2025 is part of Class 8 exam preparation. The chapters have been prepared according to the Class 8 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 8 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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Year 8 Science IGCSE (Cambridge)
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