(Applying) A car is travelling at a speed of 50 km/h. On applying brakes it covers a stopping distance. Karan carries an experiment to find how different surfaces (P, Q, R and S) affect the stopping distance. The results are shown in the table given alongside. In which case is it easier to move the car? Types of road surface PQR S Stopping distance (m) 18 15 19 27 1. 2. 3. (a) P (b) Q (c) R (d) s Which type of road provides the most friction for the car to stop? (a) P (b) Q (c) R Which one of the following ways is not used to reduce friction? (a) polishing (b) lubricating (cusing sand (d) S (d) using ball bearing
Answers & Comments
Answer:
Explanation:
Let's analyze the information provided:
Easiest to move the car: The stopping distance is an indicator of how quickly a car can come to a stop. The smaller the stopping distance, the easier it is to move the car. Looking at the given stopping distances:
P: 18 m
Q: 15 m
R: 19 m
S: 27 m
Therefore, option (b) Q has the smallest stopping distance (15 m), making it easier to move the car.
Type of road providing the most friction: Friction helps in stopping the car. The greater the stopping distance, the more friction is present. Looking at the stopping distances again:
P: 18 m
Q: 15 m
R: 19 m
S: 27 m
Therefore, option (b) Q provides the most friction for the car to stop.
Ways to reduce friction:
(a) Polishing: Polishing generally makes surfaces smoother, reducing friction.
(b) Lubricating: Lubrication reduces friction between moving parts.
(c) Using sand: Sand increases friction and is used in some cases to enhance traction.
(d) Using ball bearing: Ball bearings reduce friction between rotating parts.
Therefore, option (c) using sand is not used to reduce friction; in fact, it's used to increase it.
In summary:
Easiest to move the car: (b) Q
Type of road providing the most friction: (b) Q
Way not used to reduce friction: (c) using sand