HOTS questions on 'Friction' for Class 8 Science
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Class 8 Science, Friction - HOTS Sample questions
These HOTS questions on 'Friction' for Class 8 will test the Higher Order Thinking Skills in Science of CBSE students and NSO Science Olympiad aspirants.
Question: In a real-life scenario, why is sandpaper used on the soles of shoes by athletes participating in high jump events?
a) To increase the grip and prevent slipping
b) To reduce the friction and increase speed
c) To cushion the impact during landing
d) To maintain balance and stability
Answer: a) To increase the grip and prevent slipping
Explanation: Sandpaper, with its rough surface, increases the friction between the soles of the shoes and the ground. This helps athletes maintain a better grip, preventing slipping during takeoff and landing in high jump events.
Question: Why do cyclists wear special cycling gloves while riding?
a) To protect their hands from injuries
b) To reduce the friction between their hands and the handlebars
c) To increase the friction for better control
d) To improve aerodynamics and reduce air resistance
Answer: c) To increase the friction for better control
Explanation: The special cycling gloves have textured surfaces that increase the friction between the hands and the handlebars. This enhanced friction provides cyclists with better control and grip, especially when riding on uneven or slippery surfaces.
Question: How does the use of talcum powder on a basketball player's hands affect their ball handling skills?
a) It increases the friction, improving grip on the ball
b) It decreases the friction, allowing the ball to slip easily
c) It reduces sweat, keeping the hands dry
d) It enhances the player's focus and concentration
Answer: b) It decreases the friction, allowing the ball to slip easily
Explanation: Talcum powder reduces the friction between the basketball player's hands and the ball's surface. This enables smoother movement and facilitates quick dribbling and passing by reducing the grip between the hands and the ball.
Question: Why do car tires have treads or patterns on their surface?
a) To increase the friction for better traction on roads
b) To decrease the friction and improve fuel efficiency
c) To reduce the weight of the tires
d) To enhance the aesthetic appearance of the tires
Answer: a) To increase the friction for better traction on roads
Explanation: The treads or patterns on car tires serve to increase friction between the tires and the road surface. This improves traction, especially in wet or slippery conditions, allowing the tires to grip the road and prevent skidding or sliding.
Question: Why do ice skaters glide more smoothly on ice compared to walking on it?
a) Ice has lower friction compared to other surfaces
b) Ice provides more support to the body
c) Ice reduces the weight of the skater
d) Ice improves the balance and stability of the skater
Answer: a) Ice has lower friction compared to other surfaces
Explanation: Ice has a low coefficient of friction
Question: Why do athletes apply chalk on their hands before weightlifting?
a) To reduce the friction and increase grip
b) To improve the aesthetics of their hands
c) To keep the hands dry and prevent sweating
d) To make their hands look more muscular
Answer: a) To reduce the friction and increase grip
Explanation: Applying chalk on the hands increases friction between the hands and the weightlifting bar. This enhances the grip, allowing athletes to have a better hold on the bar and improve their lifting performance.
Question: Why are ski slopes often covered with artificial snow?
a) To make skiing more challenging
b) To reduce the friction between skis and snow
c) To improve the aesthetics of the slopes
d) To provide a softer landing in case of falls
Answer: b) To reduce the friction between skis and snow
Explanation: Artificial snow on ski slopes reduces the friction between skis and snow, allowing skiers to glide more smoothly. This enhances the overall skiing experience and enables better control and maneuverability.
Question: Why do table tennis players frequently change the rubber on their racket?
a) To decrease the speed of the ball
b) To increase the friction between the racket and the ball
c) To reduce the weight of the racket
d) To improve the visual appearance of the racket
Answer: b) To increase the friction between the racket and the ball
Explanation: Changing the rubber on a table tennis racket helps players maintain the desired level of friction between the racket and the ball. As the rubber wears out over time, replacing it ensures better grip and control, enabling players to execute various shots effectively.
Question: Why do ice hockey players frequently sharpen the blades of their skates?
a) To reduce the weight of the skates
b) To improve the aesthetics of the skates
c) To decrease the friction between the blades and the ice
d) To enhance maneuverability and control on the ice
Answer: d) To enhance maneuverability and control on the ice
Explanation: Sharpening the blades of ice hockey skates helps create a fine edge, which enhances maneuverability and control on the ice. The sharpened blades improve the player's ability to change direction
Question: Why do car racers use slick tires in dry weather conditions?
a) To increase fuel efficiency
b) To improve the visual appearance of the car
c) To reduce the weight of the tires
d) To maximize traction and minimize friction
Answer: d) To maximize traction and minimize friction
Explanation: Slick tires, with their smooth tread pattern, provide maximum contact between the tire and the road surface. This reduces friction and allows car racers to achieve optimal traction and faster speeds in dry weather conditions.
Question: Why do athletes wear spiked shoes while participating in track and field events?
a) To increase the weight of their shoes
b) To improve their balance and stability
c) To enhance the aesthetics of their footwear
d) To increase traction and grip on the track surface
Answer: d) To increase traction and grip on the track surface
Explanation: Spiked shoes have protruding spikes or studs on the sole, which penetrate the track surface. This helps athletes achieve better traction and grip, allowing them to generate more force and maintain stability during running, jumping, or throwing events.
Question: Why do construction workers wear safety gloves while handling rough materials?
a) To improve their hand dexterity
b) To reduce the visibility of their hands
c) To keep their hands warm in cold weather
d) To protect their hands from injuries and abrasions
Answer: d) To protect their hands from injuries and abrasions
Explanation: Safety gloves provide a protective barrier between construction workers' hands and rough materials, preventing injuries and abrasions. They offer cushioning and impact resistance, ensuring the safety and well-being of workers during construction activities.
Question: Why do swimmers wear swim caps during competitions?
a) To make their heads more buoyant
b) To improve their visibility in the water
c) To reduce water resistance and drag
d) To keep their hair dry
Answer: c) To reduce water resistance and drag
Explanation: Swim caps are made of smooth, hydrodynamic materials that help reduce water resistance and drag while swimming. By minimizing resistance, swimmers can move through the water more efficiently and achieve better speeds.
Question: Why do mountaineers use crampons on their boots while climbing icy surfaces?
a) To increase the weight of their boots
b) To improve their balance and stability
c) To enhance the aesthetics of their footwear
d) To provide traction and grip on icy surfaces
Answer: d) To provide traction and grip on icy surfaces
Explanation: Crampons are traction devices with sharp spikes or teeth that are attached to mountaineering boots. They dig into the icy surface, providing mountaineers with necessary traction and grip, allowing them to navigate steep and slippery terrain safely.
Question: Why do tennis players use a towel to wipe off sweat during matches?
a) To cool down their body temperature
b) To improve their grip on the racket
c) To prevent the accumulation of dirt and dust
d) To enhance the visual appearance on the court
Answer: b) To improve their grip on the racket
Explanation: Wiping off sweat with a towel helps tennis players maintain a dry grip on the racket. By removing moisture from their hands and equipment, they can prevent slippage, maintain control, and execute shots with precision during intense matches.
Question: Why do skateboarders apply wax to rails and ledges?
a) To make them more slippery
b) To increase the weight of the skateboard
c) To enhance the aesthetics of the rails and ledges
d) To reduce friction and facilitate smoother slides
Answer: d) To reduce friction and facilitate smoother slides
Explanation: Skateboarders apply wax to rails and ledges to reduce friction between their skateboard's trucks and the surface. This allows for smoother slides and grinds, enabling skateboarders to perform tricks and maneuvers more effectively.
Question: Why do archers use finger tabs or shooting gloves?
a) To protect their fingers from injuries
b) To increase the weight of the bow
c) To enhance the accuracy of their shots
d) To improve their hand-eye coordination
Answer: a) To protect their fingers from injuries
Explanation: Archers use finger tabs or shooting gloves to protect their fingers from injuries caused by the bowstring. These protective accessories provide a cushioning barrier and reduce friction, preventing discomfort and potential damage while shooting arrows.
Question: Why do bobsledders polish the runners of their sleds?
a) To increase the weight of the sled
b) To improve the visual appearance of the sled
c) To reduce friction and increase speed
d) To make it easier to steer the sled
Answer: c) To reduce friction and increase speed
Explanation: Bobsledders polish the runners of their sleds to achieve a smooth, polished surface. This reduces friction between the sled and the ice track, allowing for faster speeds and improved performance during bobsled races.
Question: Why do basketball players apply resin or grip enhancers to their hands?
a) To increase the weight of the basketball
b) To improve their shooting accuracy
c) To enhance the visual appearance of their hands
d) To ensure a better grip on the ball
Answer: d) To ensure a better grip on the ball
Explanation: Basketball players apply resin or grip enhancers to their hands to ensure a better grip on the ball. These substances increase friction between the hands and the basketball, allowing players to maintain control, dribble, and shoot more accurately during intense games.
Extra questions - Class 8 Science - Friction
Why is it difficult to walk on a wet floor?
Answer: Walking on a wet floor is difficult because the water layer makes the surface smooth. The water coating reduces friction, making it difficult for the foot to maintain a firm grasp on the floor, causing it to slip.
What causes a car to stop when the brakes are applied?
Answer: When brakes are applied, the brake pads exert frictional force on the rotating wheels. This friction converts the kinetic energy of the moving car into heat energy, causing the car to slow down and eventually stop.
Why does a pencil leave a mark on paper?
Answer: The friction between the pencil's graphite or lead and the rough surface of the paper causes the pencil to leave a mark. The pencil's tip deposits the graphite/lead material onto the paper, leaving a visible trace.
Why do our shoes wear out over time?
Answer: The constant contact and movement of our shoes against different surfaces create friction. Over time, this friction wears away the material of the shoes, causing them to gradually wear out.
Why does a rolling ball eventually come to a stop?
Answer: The rolling ball experiences friction between its surface and the surface it is rolling on. This friction opposes the motion, causing the ball to lose its kinetic energy and eventually come to a stop.
Why is it easier to slide down a slide compared to climbing up it?
Answer: Sliding down a slide is easier because the slide's smooth surface reduces friction between the sliding surface and the person's body, allowing them to slide with less resistance. Climbing up the slide requires overcoming the force of friction, making it more difficult.
Why does a matchstick need to be struck against a rough surface to light it?
Answer: When a matchstick is struck against a rough surface, the friction between the matchstick's head and the rough surface generates heat. This heat ignites the chemicals on the matchstick's head, resulting in a flame.
Why does sandpaper feel rough to touch?
Answer: Sandpaper is made up of abrasive particles on its surface. When touched, these abrasive particles create friction against the skin, resulting in a rough or coarse sensation.
Why does a rubber eraser grip onto a pencil?
Answer: Rubber erasers have a high coefficient of friction. When pressed against a pencil, the rubber's surface interacts with the pencil's surface, creating friction. This friction allows the eraser to grip onto the pencil, making it easier to erase marks.
Why is it easier to slide a heavy object on a smooth surface?
Answer: Smooth surfaces have lower friction compared to rough surfaces. When sliding a heavy object on a smooth surface, there is less resistance to overcome due to the reduced friction, making it easier to move the object.
Why do tires have tread patterns?
Answer: Tread patterns on tires provide better traction and grip on the road surface. The patterns help channel water away, improving wet-weather performance and reducing the chances of hydroplaning. The tread also increases the contact area between the tire and the road, enhancing friction and control.
Why does a bicycle chain need oiling?
Answer: Oiling the bicycle chain reduces friction between its links and moving parts. The oil forms a lubricating layer, preventing metal-to-metal contact and reducing wear and tear. This ensures smoother rotation and efficient power transfer in the bicycle's drivetrain.
Why do skaters wax the edges of their boards?
Answer: Skaters wax the edges of their boards to reduce friction between the board's edges and the surfaces they slide on. The wax creates a slippery surface, allowing smoother and faster slides while performing tricks and maneuvers.
Why do athletes wear spiked shoes for running?
Answer: Athletes wear spiked shoes to improve traction and grip during running. The spikes on the shoes' soles penetrate the track or ground, increasing the contact area and friction, thereby enhancing their ability to push off and maintain stability.
Why does a person experience air resistance while cycling?
Answer: Air resistance, also known as drag, is experienced by a cyclist due to the frictional force exerted by the air on their moving body. The cyclist needs to overcome this resistance, which increases with speed, by applying more force.
Why do sparks fly when a metal object is rubbed against a rough surface?
Answer: When a metal object is rubbed against a rough surface, such as a flint or abrasive material, the friction between the surfaces generates heat. This heat can be sufficient to ignite small particles or produce sparks, especially if the metal is highly reactive or flammable.
Why do we use oil or grease to lubricate moving parts?
Answer: Oil or grease is used to lubricate moving parts to reduce friction and wear. The lubricant forms a thin film between the surfaces, allowing them to slide smoothly over each other with minimal resistance, thus reducing heat generation and extending the lifespan of the parts.
Why is it difficult to ride a bike on a muddy trail compared to a paved road?
Answer: Riding a bike on a muddy trail is difficult because mud increases friction between the tires and the ground. This makes it harder for the tires to grip the surface, leading to reduced traction and stability compared to riding on a smooth, paved road.
Why does a ball bounce higher on a hard surface compared to a soft one?
Answer: When a ball hits a hard surface, such as a concrete floor, the surface exerts a greater force and deforms the ball momentarily. The ball then rebounds with more energy due to the high elastic potential energy stored during deformation, resulting in a higher bounce. A soft surface absorbs more of the ball's energy, resulting in a lower bounce.
Why do we sprinkle salt on icy roads during winter?
Answer: Salt is sprinkled on icy roads to lower the freezing point of water. When salt comes in contact with ice, it dissolves and forms a saline solution. This solution has a lower freezing point than pure water, causing the ice to melt and preventing further ice formation, thereby improving traction and making the roads safer to drive on.
HOTS Questions on Friction for Class 8 - PDF
The HOTS questions in the pdf sample papers will help students of grade 8 to ace their CBSE exam and the "achiever's section" of Science Olympiads.
Try to solve the higher order thinking questions in the pdf sample paper below within 60 minutes. You also have the option of attempting these questions in online mode.
The answer key to the HOTS questions on 'friction' is shared at the end of the pdf. If you want to see the solutions, you need to take the online test series.
HOTS Questions on 'Friction' for Class 8 - Online test
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