Law Of Motion Book Back Questions 10th Science Lesson 1

10th Science Lesson 1

1] Law Of Motion

Book Back Questions with Answer and Do You Know Box Content

Choose the best answers:

1. Inertia of a body depends on

(a) Weight of the object

(b) Acceleration due to gravity of the planet

(c) Mass of the object

(d) Both a & b

2. Impulse is equal to

(a) Rate of change of momentum

(b) Rate of force and time

(c) Change of momentum

(d) Rate of change of mass

3. Newton’s III law is applicable

(a) For a body is at rest

(b) For a body in motion

(c) Both a & b

(d) Only for bodies with equal masses

4. Plotting a graph for momentum on the X-axis and time on Y-axis. Slope of momentum – time graph gives

(a) Impulsive force

(b) Acceleration

(c) Force

(d) Rate of force

5. In which of the following sport the turning of effect of force used

(a) Swimming

(b) Tennis

(c) Cycling

(d) Hockey

6. The unit of ‘g’ is ms^-2. It can be also expresses as

(a) cms^-1

(b) Nkg^-1

(c) Nm²kg^-1

(d) cm²s^-2

7. One-kilogram force equals to

(a) 9.8 dyne

(b) 9.8 x 10⁴ N

(c) 98 x 10⁴ dyne

(d) 980 dyne

8. The mass of a body is measured on planet Earth as M kg. When it is taken to a planet of radius half that of the Earth then its value will be ________________ kg

(a) 4 M

(b) 2 M

(c) M/4

(d) M

9. If the Earth shrinks to 50% of its real radius its mass remaining the same, the weight of a body on the Earth will

(a) Decrease by 50%

(b) increase by 50%

(c) Decrease by 25%

(d) increase by 300%

10. To project the rockets which of the following principle(s) is / (are) required?

(a) Newton’s third law of motion

(b) Newton’s law of gravitation

(c) Law of conservation of linear momentum

(d) Both a and c

Fill in the blanks:

1. To produce a displacement _________________ is required.

a. Mass

b. Momentum

c. Torque

d. Force

2. Passengers lean forward when sudden brake is applied in a moving vehicle. This can be explained by ________________.

a. the inertia of motion

b. acceleration due to gravity

c. Speed of the vehicle

d. Mass of the vehicle

3. By convention, the clockwise moments are taken as ___________ and the anticlockwise moments are taken as _________________.

a. Increasing, Decreasing

b. Positive, Negative

c. Negative, Positive

d. Decreasing, Increasing

4. _______________ is used to change the speed of car.

a. Torque

b. Power

c. acceleration

d. External Force

5. A man of mass 100 kg has a weight of _____________ at the surface of the Earth.

a. 0.98N

b. 98×10^{2 N}

c. 0N

d. 980N

State true or false. If false, correct the statement:

1. The linear momentum of a system of particles is always conserved.

2. Apparent weight of a person is always equal to his actual weight.

3. Weight of a body is greater at the equator and less at the polar region.

4. Turning a nut with a spanner having a short handle is so easy than one with a long handle.

5. There is no gravity in the orbiting space station around the Earth. So the astronauts feel weightlessness.

Match the following:

Column I Column II

a. Newton’s I law – propulsion of a rocket

b. Newton’s II law – stable equilibrium of a body

c. Newton’s III law – law of force

d. Law of conservation of Linear momentum – flying nature of bird

Consider the statements given below and choose the correct option:

Mark the correct choice as

(a) If both assertion and reason are true and reason is the correct explanation of assertion

(b) If both assertion and reason are true but reason is not the correct explanation of assertion

(c) If assertion is true but reason is false

(d) If assertion is false but reason is true

1. Assertion: The sum of the clockwise moments is equal to the sum of the anticlockwise moments.

Reason: The principle of conservation of momentum is valid if the external force on the system is zero.

2. Assertion: The value of ‘g’ decreases as height and depth increases from the surface of the Earth.

Reason: ‘g’ depends on the mass of the object and the Earth.

Answers:

Choose the best answer:

1. Mass of the object 2. Change of Momentum 3. Both a and b 4. Force

5. Cycling 6. Nkg^-1 7.98×10⁴ dyne 8. M/4 9. Decrease by 25% 10. Newton’s third law of motion

Fill in the Blanks:

1.Force 2. Inertia of the motion 3. Positive, Negative 4. Acceleration 5. 980N

True or False:

1.False (The Linear momentum of a system of particles is always conserved if no external force acts on it)

2.False (Apparent weight of a person varies according to the vertical movement of that person)

3.False (Weight of a body is greater in the polar region and lesser in the equatorial region)

4.False (Turning a nut with a short handle is harder than the one with a long handle)

5.False (There is gravity in the orbiting space and the astronauts are in the state of free fall)

Match the following:

a. stable equilibrium of a body

b. flying nature of bird

c. propulsion of a rocket

d. law of force

Assertion and Reasoning:

1. Both assertion and reason are true but reason is not the correct explanation of assertion
2. Assertion is true but reason is false

(mass ‘m’ depends on the gravity ‘g’ of the earth)