Physics Past Paper PDF (2023-24)

(ii) From Eq. (7.7) we have 2 a s = v2 – u2 = v2 – 0 Thus, v s= Example 7.7 The brakes applied to a car produce an acceleration of 6 m s-2 in the opposite direction to the motion. If the car takes 2 s to stop after the application of brakes, calculate the distance it travels during this time. 2 2a –...

(ii) From Eq. (7.7) we have 2 a s = v2 – u2 = v2 – 0 Thus, v s= Example 7.7 The brakes applied to a car produce an acceleration of 6 m s-2 in the opposite direction to the motion. If the car takes 2 s to stop after the application of brakes, calculate the distance it travels during this time. 2 2a –1 2 = (20 m s ) 2×(1/15) m s Solution: –2 We have been given a = – 6 m s–2 ; t = 2 s and v = 0 m s–1. From Eq. (7.5) we know that v = u + at 0 = u + (– 6 m s–2) × 2 s or u = 12 m s–1. From Eq. (7.6) we get = 3000 m = 3 km The acceleration of the train is 1 m s– 2 15 and the distance travelled is 3 km. s=ut+ Example 7.6 A car accelerates uniformly –1 –1 from 18 km h to 36 km h in 5 s. Calculate (i) the acceleration and (ii) the distance covered by the car in that time. = (12 m s–1 ) × (2 s) + Thus, the car will move 12 m before it stops after the application of brakes. Can you now appreciate why drivers are cautioned to maintain some distance between vehicles while travelling on the road? We are given that u = 18 km h–1 = 5 m s–1 v = 36 km h–1 = 10 m s–1 and t = 5s. (i) From Eq. (7.5) we have = Q v–u t 10 m s-1 – 5 m s -1 5s = 1 m s–2 (ii) From Eq. (7.6) we have s=ut+ uestions 1 at 2 2 = 5 m s–1 × 5 s + 1 (–6 m s–2 ) (2 s)2 2 = 24 m – 12 m = 12 m Solution: a= 1 at2 2 1 × 1 m s–2 × (5 s)2 2 = 25 m + 12.5 m = 37.5 m –2 The acceleration of the car is 1 m s and the distance covered is 37.5 m. 82 1. A bus starting from rest moves with a uniform acceleration of 0.1 m s-2 for 2 minutes. Find (a) the speed acquired, (b) the distance travelled. 2. A train is travelling at a speed of 90 km h–1. Brakes are applied so as to produce a uniform acceleration of – 0.5 m s-2. Find how far the train will go before it is brought to rest. 3. A trolley, while going down an inclined plane, has an acceleration of 2 cm s-2. What will be its velocity 3 s after the start? SCIENCE Rationalised 2023-24