# ICSE Worksheet for chapter-4 Motion in One Dimension class 9

## Summary

• REST AND MOTION, DISTANCE AND DISPLACEMENT
• SPEED AND VELOCITY, ACCELERATION AND RETARDATION
• MOTION UNDER GRAVITY, UNIFORMLY ACCELERATED MOTION

### SECTION 1 – OBJECTIVE

Q1. A body when projected up goes to height ‘h’ in time ’t’ and then returns back at the point of projection. The incorrect statement is:

1. The displacement is zero
2. The average velocity is 2h/t.
3. The final speed is same as the initial speed
4. Acceleration is constant.

Q2. Unit of retardation is:

1. m/s
2. m/s2
3. m
4. m s2

Q3. The velocity of a body starting from rest is directly proportional to time. Which is uniform?

1. Velocity only
2. Acceleration only
3. Both velocity and acceleration
4. Neither velocity nor acceleration

Q4. For a uniformly accelerated motion, the velocity-time graph is:

1. A straight line parallel to the time axis
2. A straight line perpendicular to the time axis
3. A straight line inclined to the time axis
4. A curve

Q5. A body is projected vertically upwards with an initial velocity. If acceleration due to gravity is g, the time for which it remains in air is:

1. u/g
2. u.g
3. 2u/g
4. u/2g

Q6. A body is dropped from top of tower. The quantity which remains constant is:

1. Displacement
2. Speed
3. Velocity
4. Acceleration

Q7. A pebble is thrown vertically upwards with a speed of 20 m/s. How high will it be after 2 s?

(g = 10 m/s2)

1. 10 m
2. 20
3. 15 m
4. 22 m

Q8. A bullet initially moving with a velocity 20 m/s strikes a target and comes to rest after penetrating a distance 10 cm in the target. The retardation caused by the target is:

1. 2000 m/s2
2. 2550 m/s2
3. 3000 m/s2
4. 4500 m/s2

Q9. Slope of displacement v/s time graph is:

1. Velocity
2. Displacement
3. Acceleration
4. Time

Q10. The shortest path travelled by any object is:

1. Distance
2. Displacement
3. Velocity
4. Acceleration

#### SECTION II - SUBJECTIVE

Q1. Differentiate between following:

1. Distance& Displacement
2. Uniform acceleration & Variable acceleration
3. Speed& velocity

Q2. A bullet of mass 0.006 kg travelling at 120 m/s penetrates deeply into a fixed target and is brought to rest in 0.01 s. Calculate:

1. The distance of penetration in the target, and
2. The average retarding force exerted on the bullet.

Q3. Derive an expression for the distance covered in the nth second by a body moving with uniform acceleration.

Q4. A train is moving with a velocity of 90 km/h. When the brakes are applied, the retardation produced is 0.5 m/s2. Find (a) the velocity after 10s (b) The time taken by the train to come to rest.

Q5. A vehicle is accelerating on a straight road. Its velocity at any instant is 30 km/h. After2s, it is 33.6 km/h and after further 2s, it is 37.2 km/h, find the acceleration of the vehicle in m/s2. Is the acceleration uniform?

Q6. A car travels first 30 km with a uniform speed of 60 km/h and the next 30 km with a uniform speed of 40 km/h. Calculate:

1. The total time of journey
2. The average speed of car

### Solutions

Objective Problems

 1.(B) 2.(B) 3.(B) 4.(C) 5.(C) 6.(D) 7.(B) 8.(A) 9.(A) 10.(B)

Subjective Problems

Q2. 1. s=0.6m

2. F =72N

Q4. 1. v = 20m/s

2. t = 50s

Q5. The value of acceleration is 0.5m/s2. Yes the acceleration is uniform.

Q6. 1.Total time of journey = 75min

2. Average speed of car is 48km/h

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