Force and Motion

Question 1

Your velocity relative to the sun ?

Answer 1

30 km/s

Question 2

Speed
Velocity
Change in velocity
(positive or negative?)

Answer 2

Speed can only be positive? and never negative.
Velocity can be positive and negative.
Change in velocity can be positive or negative.

Question 3

Direction of V, del V, a and P(momentum), del P with respect to force.

Answer 3

Force will always have same direction as (a), (del V) and (del P).
Velocity is positive/negative/increasing/decreasing will decide if V and P will have same direction as force or opposite.

Question 4

Can displacement be zero?

Answer 4

For a moving object, distance can never be zero but displacement can be zero.

Question 5

Speed of moon around earth

Answer 5

1000 m/s

Question 6

speed of sound in air

Answer 6

333 m/s

Question 7

speed of earth around sun

Answer 7

29600 m/s

Question 8

Slope of distance-time graph?

a) speed
b) velocity

Answer 8

Speed

As distance always increases, the slope can never be negative.

Question 9

Slope of displacement-time curve?

Answer 9

Velocity

Question 10

Slope of displacement time graph?

positive or negative?

Answer 10

Can be both positive and negative!

Question 11

Property of an object that resists acceleration?

Answer 11

Inertia. Property of object tending to maintain the state of rest or uniform motion.

Question 12

Quantitative measure of inertia is?

Answer 12

Mass of object.

Question 13

Force is measure and defined by which law?

Answer 13

Force is defined as the external effect which can change the state of motion or steady state of a body by law of inertia.
Force is measured by 2nd law of motion.

Question 14

At what speed newtonian mechanics is valid?

Answer 14

Speeds much lower than speed of light.
lesser than 1% of speed of light.
lesser than 3000 km/s. = 3 × 10^6 m/s
lesser than 3 million m/s

Question 15

What is quantity of motion called ?

Answer 15

Momentum

Question 16

Unit of momentum

Answer 16

Kg m/s = N s

Question 17

More general form of second law of motion?

Answer 17

F= m(Vf-Vi)/t
F= del P/ del t

Question 18

Collision of tennis balls?

Answer 18

Inelastic Collision

Question 19

Hard ball collision with marble floor?

Answer 19

Elastic Collision

Question 20

Collision can occur even when the objects don’t necessarily touch.
True or False?

Answer 20

True. e.g proton and helium nucleus

Question 21

Billiard ball collision

Answer 21

Approximately Elastic. Would be truly elastic if produced no sound.

Question 22

True elastic collisions occur in?

Answer 22

Atomic and sub atomic particles.

Question 23

Thrust produced by the engine on the body?

Answer 23

mv (where m is mass per sec)

Question 24

A typical rocket consumes about kg/s of fuel and and ejects the burnt gasses at speeds of over m/s.

Answer 24

10,000 kg/s

4000 m/s

Question 25

Amount of fuel of a rocket?

Answer 25

80% of launch mass of rocket consists of fuel.

Question 26

Trajectory of projectile?

Answer 26

Parabola

Question 27

Things to remember in projectile motion

Answer 27

1. Horizontal component of velocity remains constant
2. a (x)= zero
3. a(y)= g
4. Velocity at maximum height= v(x)

Question 28

Ballistic missile?

Answer 28

Unpowered and unguided.
For short ranges and flat Earth approximation.
Trajectory is called ballistic trajectory, is parabolic.
Dragless ballistic trajectory for spherical Earth should be elliptical.

Question 29

Time of projectile is related to horizontal or vertical motion?

Answer 29

Vertical

Question 30

Range = Height at angle?

Answer 30

tan^-1 (4)

Question 31

Relation bw height and time

Answer 31

8H=gT^2

Question 32

Relation bw height and range

Answer 32

R(max)=4H