Forces, Work Done and Energy

Question 1

Formula for GPE

Answer 1

Weight*Height = mgh
g is 10N/kg on Earth
Moon is 1/6 of that

Question 2

Formula for weight

Answer 2

mass*gravity
Units: N/kg

Question 3

SI Unit for Energy, Work Done

Answer 3

Joule: J

Question 4

SI Unit for Forces

Answer 4

Newton: N

Question 5

SI Unit for length

Answer 5

metre

Question 6

SI Unit for mass

Answer 6

kg

Question 7

SI Unit for pressure

Answer 7

Pa
1Pa = 1N/m**2

Question 8

Formula for pressure

Answer 8

Force/Area

Question 9

What is CPE

Answer 9

Stored energy
In fuel or food that can be released during chemical reactions

Question 10

What is EPE

Answer 10

Energy object has when stretched or compressed

Question 11

What is GPE

Answer 11

More mass or height –> more GPE

Question 12

What is KE

Answer 12

Motion
More mass or speed –> more KE

Question 13

What can energy be transferred as

Answer 13

Heat
Light
Sound
Electrical Energy

Question 14

What is a force

Answer 14

Push or pull
cause change in size, speed and direction of motion
Measured using spring balance

Question 14

What is the principle of conservation of energy

Answer 14

Energy cannot be created or destroyed, but energy can be transferred to one object or another or converted to one form or another

Question 15

Effects of force

Answer 15

Causes a stationary object to move
Speeds up a moving object
Slows down a moving object
Stops a moving object
Change the direction of moving object
cause a turning effect in objects
exert pressure on objects

Question 16

Types of contact forces

Answer 16

Elastic force
Frictional force

Question 17

What is elastic force

Answer 17

force acting on stretched or compressed elastic object to return to its original shape

Question 18

What is friction

Answer 18

Oppose motion between surface in contact
acts in opposite direction of applied force

Question 19

Effects of friction

Answer 19

Good:
Generate heat (light match)
moving vehicles slow down when needed
walk withoutslipping
hold objects
Bad:
Unwanted heat generated
unwanted slowing down or stopping of motion
wear and tear of objects

Question 20

How to reduce friction

Answer 20

Smooth/polished surface
Wheels and rollers
use ball bearings around axles in bicycles and cars
use lubricants
use air as cushion
adopt a streamline shape

Question 21

Types of non-contact forces

Answer 21

Magnetic force
Weight
Electrostatic force

Question 21

What is weight

Answer 21

gravitational force acting on object
can be 0 when there is no gravitational field strength
has both magnitude and direction
measured with spring balance

Question 22

What is electrostatic force

Answer 22

force that acts between 2 charged particles
like charge repel
unlike attract. this force acting on the positive and negative charges is called electrostatic forces of attraction

Question 22

What is mass

Answer 22

Amount of matter in a body only a magnitude SI Unit: kg Measured with beam balance or calibrated electronic balance

Question 23

What is net/resultant force

Answer 23

If speed and direction of moving object is constant, no net/resultant force balanced forces --> no net force state of object not changed when no net force --> rest at first still rest, motion at first motion still at THE SAME speed If forces are unbalanced --> speed/direction of object would change

Question 24

What is atmospheric pressure

Answer 24

Pressure exerted by air in earth's atmosphere

Question 24

What is liquid pressure

Answer 24

Pressure exerted when an object is immersed in it

Question 24

What is liquid pressure affected by

Answer 24

Deeper the object, more liquid pressure