P Hysics FOR 9TH-a Ssigmnent PDF

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physics, science that deals with the structure of matter and the interactions between the fundamental constituents of the observable universe. In the broadest sense, physics (from the Greek physikos) is concerned with all aspects of nature on both the macroscopic and submicroscopic levels....

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Subject: - Physics Topic Name: - Number system, Triangles, Linear equation in two variables Batch: - 9th PSAT Date: - 19-12-2021

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Which of the following statements is not correct for an object moving along a straight path in an accelerated motion? (a) Its speed keeps changing (b) Its velocity always changes (c) It always goes away from the Earth (d) A force is always acting on it The inertia of an object tends to cause the object (a) to increase its speed (b) to decrease its speed (c) to resist any change in its state of motion (d) to decelerate due to friction An object of mass 2 kg is sliding with a constant velocity of 4 ms-1 on a frictionless horizontal table. The force required to keep the object moving with the same velocity is (a) 32 N (b) 0 N (c) 2 N (d) 8 N Rocket works on the principle of conservation of (a) mass (b) energy (c) momentum (d) velocity If a car is traveling at 8 ms−1 accelerates uniformly at 2 ms−2, its velocity after 5 seconds will be (a) 20 ms−1 (b) 23 ms−1 −1 (c) 25 ms (d) 28 ms−1 If a sprinter runs a distance of 100 metres in 9.83 seconds, calculate his average speed in km/h. (a) 36.18 km/h (b) 36.62 km/h (c) 35.15 km/h (d) 34.62 km/h Suppose a boy is enjoying a ride on a marry-go-round which is moving with a constant speed of 10 m/s. It implies that the boy is: (a) At rest (b) Moving with no acceleration (c) In accelerated motion (d) Moving with uniform velocity A car of mass 1000 kg is moving with a velocity of 10 m/s. If the velocity-time graph for this car is a horizontal line parallel to the time axis, then the velocity of the car at the end of 25 s will be: (a) 40 m/s (b) 25 m/s (c) 10 m/s (d) 250 m/s The ratio of the heights from which two bodies are dropped is 3:5 respectively. The ratio of their final velocities is: (a) 9: 25 (b) √ 3: √ 5 (c) 5 : 3 (d) √5 : √3 The speedometer of a car measures (a) average speed (b) instantaneous speed (c) acceleration (d) none of the above An aircraft travelling at 600km/h accelerates steadily at 10km/h per second. Taking the speed of sound as 1100km/h at the aircraft's altitude, how long will it take to reach the 'sound barrier'? (a) 60 sec (b) 50 sec (c) 70 sec (d) 40 sec A particle is moving in a circular path of radius r. What would be the displacement after half a circle? (b) r (a) πr EDU PACE COACHING INSTITUTE,UNA-CHANDIGARH HIGHWAY, OPP. DEGREE COLLEGE UNA (H.P.) Page Contact no. 9459800801, 802, 803 email: [email protected] www.educpace.com

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(c) 2 πr (d) 2r The speed – time graph of a car is given here. Using the data in the graph calculate the total distance covered by the car.

(a) 1250 m (c) 1500 m 14.

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(b) 875 m (d) 870 m

Four cars A, B, C and D are moving on a levelled, straight road. Their distance time graphs are shown in the figure below. Which of the following is the correct statement regarding the motion of these cars?

(a) Car A is faster than car D (b) Car B is the slowest (c) Car D is faster than car C (d) Car C is the slowest Given below is the velocity-time graph for the motion of the car. What does the nature of the graph show ? Also find the acceleration of the car.

(a) Uniformly accelerated motion, 0.5 ms-2 (b) Non-Uniformly accelerated motion, 0.5 ms-2 (c) Uniformly accelerated motion, 1 ms-2 (d) Non-Uniformly accelerated motion, 1 ms-2 16.

The graph given below shows the positions of a body at different times. Calculate the speed of the body as it moves from (i) A to B (ii) B to C and (iii) C to D.

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(a) (i) 1cm/s, (ii) 2 cm/s, (iii) 2cm/s (b) (i) 1cm/s, (ii) 0, (iii) 1 cm/s (c) (i) 1cm/s, (ii) 0, (iii) 2cm/s (d) (i) 2cm/s, (ii) 1 cm/s, (iii) 2cm/s From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m/s. Calculate the initial recoil velocity of the rifle. (a) 0.4378 m/s (b) 0.4375 m/s (c) 0.4333 m/s (d) 0.3333 m/s A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400 m in 20 s. Find its acceleration. Find the force acting on it if its mass is 7 tonnes (Hint : 1 tonne = 1000 kg). (a) 15000 N (b) 16000 N (c) 7000 N (d) 14000 N Using a horizontal force of 200 N, we intend to move a wooden cabinet across a floor at a constant velocity. Given that the coefficient of friction between wooden cabinet and floor is 0.2 and mass of the cabinet is 100 kg. What is the friction force that will be exerted on the cabinet?

(a) 100 N (b) 0 N (c) 200 N (d) 50 N The coin remains at rest in the figure shown. This is due to

(a) inertia of rest (b) two forces act on the coin which balance each other (c) no unbalanced force acts on it (d) all of these

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Solution 4. (b) 0 N From newton’s Ist law of motion, since there is no external force acting on the object it will remain in its original state of motion. Hence, zero force is required to keep the object moving with constant velocity, correct answer is B. 12. Displacement = AB = Shortest distance between initial and final positions = r + r = 2r

15. The nature of the graph shows that velocity changes by equal amounts in equal intervals of time. For a uniformly accelerated motion, velocity-time graph is always a straight line. As we know, acceleration is equal to the slope of the graph

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(i) The distance-time graph represents the line AB which shows the speed of the body. So, Speed = Distance/ Time =3cm/(5−2)s = 1 cm/s (ii) The distance-time graph shows that the body is at rest between graph line B to C, it means no movement. So speed is zero i.e., Speed = Distance/ Time =0/(7−5)s = 0/2s = 0 (iii) The distance-time graph represents the line CD which shows the speed of the body. So, Speed = Distance /Time =(7−3)cm/(9−7)s= 2 cm/s

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As the wooden cabinet moves across the floor at a constant velocity and the force applied is 200 N. Hence the frictional force that will be exerted on the cabinet will be less than 200 N.

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the time taken by a train to slow down from 80 kmh-1 to 20 kmh-1 with a uniform deceleration of 2 ms-2 is (a) 9 s (b)10 s (c)8.3 s (d)8.4 s EDU PACE COACHING INSTITUTE,UNA-CHANDIGARH HIGHWAY, OPP. DEGREE COLLEGE UNA (H.P.) Contact no. 9459800801, 802, 803 email: [email protected] www.educpace.com Page

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Ans c If a car is traveling at 8 ms−1 accelerates uniformly at 2 ms−2, its velocity after 5 seconds will be (a) 20 ms−1 (b) 23 ms−1 −1 (c) 25 ms (d) 28 ms−1 ans(b) The equations of motion for bodies moving with uniform acceleration are of (a)2 types (b)4 types (c)3 types (d)5 types Ans c If a sprinter runs a distance of 100 metres in 9.83 seconds, calculate his average speed in km/h. (a) 36.18 km/h (b) 36.62 km/h (c) 35.15 km/h (d) 34.62 km/h Solution Total distance travelled=100m Total time taken = 9.83 sec Average speed = Total distance travelled/ Total time taken =100/9.83 =10.172m/s Averge speed in km/h:

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10.172 x(3600/1000)=36.62 km/h An aircraft travelling at 600km/h accelerates steadily at 10km/h per second. Taking the speed of sound as 1100km/h at the aircraft's altitude, how long will it take to reach the 'sound barrier'? Solution Initial velocity, u = 600 km/h Final velocity, v = 1100 km/h Acceleration = 10 km/h/s = 600 km/h2 From relation, a = (v-u)/t t = (v-u)/a t = (1100-600)/600 = 500/600 = 5/6 hr = 50 sec

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Suppose a boy is enjoying a ride on a marry-go-round which is moving with a constant speed of 10 m/s. It implies that the boy is: (a) At rest (b) Moving with no acceleration (c) In accelerated motion (d) Moving with uniform velocity answer: (c) In accelerated motion Which of the following can sometimes be ‘zero’ for a moving body? i. Average velocity ii. Distance travelled iii. Average speed iv. Displacement (a) Only (i) (b) (i) and (ii) (c) (i) and (iv) (d) Only (iv) Answer:(c) (i) and (iv) When a car driver travelling at a speed of 10 m/s applies brakes and brings the car to rest in 20 s, then the retardation will be: (a) + 2 m/s2 (b) − 2 m/s2 EDU PACE COACHING INSTITUTE,UNA-CHANDIGARH HIGHWAY, OPP. DEGREE COLLEGE UNA (H.P.) Page Contact no. 9459800801, 802, 803 email: [email protected] www.educpace.com

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(c) − 0.5 m/s2 (d) + 0.5 m/s2 2 Answer (d) + 0.5 m/s Which of the following is most likely not a case of uniform circular motion? (a) Motion of the earth around the sun (b) Motion of a toy train on a circular track c) Motion of a racing car on a circular track (d) Motion of hours’ hand on the dial of a clock Answer(c) Motion of a racing car on a circular track A car of mass 1000 kg is moving with a velocity of 10 m/s. If the velocity-time graph for this car is a horizontal line parallel to the time axis, then the velocity of the car at the end of 25 s will be: (a) 40 m/s (b) 25 m/s (c) 10 m/s (d) 250 m/s Answer: 10m/s The numerical ratio of displacement to distance for a moving object is: (a) Always less than 1 (b) Equal to 1 or less than 1 (c) Always more than 1 (d) Equal to 1 or more than one Anwer: (b) Equal to 1 or less than 1 Odometer of automobiles records (a) average speed (b) instantaneous speed (c) distance travelled (d) acceleration ► (c) distance travelled Which of the following situations are not possible? (a) A body moving with constant acceleration but with zero velocity. (b) A body moving horizontally with an acceleration in vertical direction (c) A body moving with a constant velocity in an accelerated motion (d) all of the above ► (c) The time taken by a train to slow down from 80 kmh-1 to 20 kmh-1 with a uniform deceleration of 2 ms-2 is (a) 9 s (b) 10 s (c) 8.3 s (d) 8.4 s ► (c) 8.3 s A body moves in a uniform circular motion (a) it is moving with constant velocity. (b) its acceleration is zero (c) the body has an acceleration (d) none of the above ► (c) the body has an acceleration A racing car has a uniform acceleration of 6 m/s2. In 10s it will cover: (a) 300m (b) 100m (c) 200m (d) 350m ► (a) 300m If car A is at 40 km/h and car B is at 10 km/h in the opposite direction, what is the velocity of the car A relative to the car B? (a) 40 km/h (b) 50 km/h (c) 10 km/h (d) 30 km/h ► (b) 50 km/h Distance covered by a body from velocity-time graph is (a) Equal to the slope of the graph. (b) Area under the graph. (c) Is denoted by a line parallel to the time axis at any point on the distance axis. (d) Is denoted by a line parallel to the distance axis at any point on the time axis. ► (b) Area under the graph. EDU PACE COACHING INSTITUTE,UNA-CHANDIGARH HIGHWAY, OPP. DEGREE COLLEGE UNA (H.P.) Contact no. 9459800801, 802, 803 email: [email protected] www.educpace.com Page

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What is the slope of distance-time graph when object is at rest? (a) Decreases continuously (b) Zero (c) Increases continuously (d) One ► (b) Zero The ratio of the heights from which two bodies are dropped is 3:5 respectively. The ratio of their final velocities is: (a) 9: 25 (b) √ 3: √ 5 (c) 5 : 3 (d) √5 : √3 ► (b) √ 3: √ 5 To describe the motion of an object we first specify a (a) The acceleration of the body (b) Reference point (c) The speed (d) The direction of motion ► (b) Reference point A body performs an accelerated motion, with uniform speed. The motion of body is (a) Linear (b) Circular (c) Parabolic (d) Irregular ► (b) Circular If the velocity of a body is reducing, it is said to have (a) Negative acceleration (b) Retardation (c) Positive acceleration (d) Both (a) and (b) ► (d) Both (a) and (b) The area under the velocity – time graph gives the (a) acceleration of the body (b) displacement of the body (c) velocity of the body. (d) distance of the body. ► (b) displacement of the body A body starting at a point, say A, reaches, say B, ahead in a straight line and returns back to A. Then there is (a) positive displacement (b) negative displacement (c) zero displacement (d) cannot be said ► (c) zero displacement The speed at any instant of time is known as (a) velocity (b) given speed (c) average speed (d) instantaneous speed ► (d) instantaneous speed If we get a curve line in displacement – time graph then the velocity is (a) constant (b) non-uniform (c) uniform (d) decreasing ► (b) non-uniform Speed of 90 km/h when expressed in m/s is (a) 2.5 (b) 90000 (c) 250 (d) 25 ► (d) 25 The area under the speed-time graph gives the ________. (a) velocity (b) distance EDU PACE COACHING INSTITUTE,UNA-CHANDIGARH HIGHWAY, OPP. DEGREE COLLEGE UNA (H.P.) Page Contact no. 9459800801, 802, 803 email: [email protected] www.educpace.com

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(c) acceleration (d) time ► (b) 1 km/ h = ________ m/s (a) 3/50 (b) 18/5 (c) 50/3 (d) 5/18 ► (d) 5/18 The slope of the distance-time graph is: (a) Distance (b) acceleration (c) Speed (d) Displacement ► (c) Speed Which of the quantities – speed, time, velocity and acceleration have the same SI unit? (a) speed, velocity (b) Acceleration, time. (c) velocity, time (d) velocity, acceleration ► (a) speed, velocity The equations of motion can be derived by using: (a) Distance – time graph (b) Velocity – time graph for non-uniform acceleration (c) Displacement time graph (d) Velocity – time graph for uniform acceleration ► (d) Velocity – time graph for uniform acceleration What is the average velocity of a car that moved 60 km in 3 hours? (a) 60 km/h (b) 20 km/h (c) 30 km/h (d) 10 km/h ► (b) 20 km/h Speed of sound in water is 1500 m s-1, depth of water when reflected sound waves are detected after 0.40 s is (a) 700 m (b) 600 km (c) 600 m (d) 750 km ► (c) 600 m The ______ of a distance versus time graph is speed. (a) slope (b) y-intercept (c) origin (d) none of the above ► (a) slope The speedometer of a car measures (a) average speed (b) instantaneous speed (c) acceleration (d) none of the above ► (b) instantaneous speed A stone is dropped from the top of a building which is 180 meters high. If the stone hits the ground after 6 seconds, its final velocity will be (a)40 ms−1 (b)50 ms−1 −1 (c)60 ms (d)110 ms−1 (c)ans The rest state and motion of the body are (a) non relative (b)not related (c) relative (d)none of above (c) answr A cyclist completes a half-round of a circular track of radius 420 meters in 3 minutes. Its speed will be (a)5 ms−1 (c)10 ms−1

(b)8 ms−1 (d)7.33 ms−1

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(d) answ A tennis ball hits vertically upward with the velocity of 25ms−1 and takes 4 s to reach the highest point. The maximum height reached by the ball is (a) 45 m (b)55 m (c)30 m (d)50 m (b)ans The length of a path between 2 points is called (a)displacement (b)distance (c)position (d)velocity (c)ans

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