forces

Question 1

force

Answer 1

A force is an interaction between two objects that may cause a change in motion.
The SI unit for force is the newton (N).
Force is a vector quantity.

Question 2

A resultant force

Answer 2

is the single force that has the same effect as all the forces acting on an object combined.

Question 3

Newton’s first law of motion

Answer 3

An object will remain at rest or in constant motion unless an unbalanced force acts upon it.

Question 4

equilibrium

Answer 4

An object is in equilibrium if the resultant force (and moment) acting upon that object is zero.

Question 5

Newton’s second law of motion

Answer 5

The resultant force acting on an object equals the product of its mass and the acceleration of the object in the same direction.
F = m a

Question 6

Newton’s third law of motion

Answer 6

When an object applies a force on a second object, then the second object applies an equal and opposite force on the first object.
FB,A = - FA,B
This law tells us 4 characteristics:
1st: forces always occur in pairs.
2nd: action and reaction are equal in magnitude.
3rd: action and reaction act opposite to one another.
4th: action and reaction act on different objects.

Question 7

terminal velocity

Answer 7

An object achieves terminal velocity in a fluid when the upward forces (air resistance) balance the downward forces (weight/gravity).

Question 8

Friction

Answer 8

is the resistive force
between two surfaces sliding
against each other.

Question 9

Thinking distance

Answer 9

is the distance traveled between detecting a hazard and applying the brakes.

Question 10

Braking distance

Answer 10

is the distance traveled between applying the brakes and coming to rest.

Question 11

Centripetal force

Answer 11

he resultant force that keeps an object in uniform circular motion.

Question 12

elastic deformation

Answer 12

A force applied to an object causes an elastic deformation if the object returns to its original shape when the force is removed.

Question 13

plastic deformation.

Answer 13

when a force is applied on an object it is plastic deformation if the object does not return to its original shape,

Question 14

spring and load

Answer 14

A spring is a mechanical device that stretches when a force is applied. If it is applied by a weight hanging at the end of a spring, it is called load.

Question 15

the extension of a spring

Answer 15

is the increase in its length due to the application of a force.

Question 16

Hooke’s law

Answer 16

The extension of a spring is directly proportional to the load applied to it, provided the limit of proportionality is not exceeded.
F = k x

Question 17

stiffness

Answer 17

The stiffness (symbol: k) of a spring is the constant of proportionality between load and extension.