Forces

Question 1

what effect does a force have on a stationary object?

Answer 1

causes a stationary object to move

Question 2

what effect does a force have on a moving object?

Answer 2

it increases or decreases its speed; it changes its direction

Question 3

newton’s first law of motion

Answer 3

every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it.

Question 4

if the resultant force acting on an object is zero,

Answer 4

the forces acting on the object are balanced, and there is no acceleration.

a stationary object will remain at rest and a moving object will continue moving at uniform velocity.

Question 5

newton’s second law of motion

Answer 5

when a resultant force acts on an object of a constant mass, the object will accelerate in the direction of the resultant force. the product of mass and acceleration of the object gives the resultant force.

Question 6

how do we calculate resultant force?

Answer 6

Fnet (resultant force in N) = m (mass of object) x a (acceleration of object in m s^-2)

Question 7

newton’s third law of motion

Answer 7

for every action, there is an equal and opposite reaction, and they act on mutually opposite bodies.

Question 8

what are the positive effects of friction?

Answer 8

we can walk without slipping, moving vehicles are able to slow down when needed

Question 9

what are the negative effects of friction?

Answer 9

vehicles and machines are less efficient due to energy loss from friction, moving parts in vehicles and machines suffer wear and tear.

Question 10

how can we reduce friction?

Answer 10

• use wheels in trolleys to move heavy objects
• use ball bearings and apply lubricants in moving parts of machines to reduce wear and tear
• polish surfaces
• use air cushion in hovercrafts and maglev trains

Question 11

how can we increase friction?

Answer 11

• treads in tyres that channel water out from under the tyres to improve friction on wet roads
• parachute used by skydiver to increase air resistance
• chalk powder used by rock climber to absorb sweat and increase friction on rock