P9 Forces

Question 1

What’s the definition of scalar?

Answer 1

Quantities that only have a magnitude (e.g., distance and speed

Question 2

What does Vector mean?

Answer 2

Quantities that have magnitude and a direction (e.g., velocity and force)

Question 3

What can a force be?

Answer 3

It can be a push or pull on an object caused by an interaction with another object. Forces are vector quantities.

Question 4

Are forces scalar or vector?

Answer 4

Vector quantities

Question 5

When do contact forces occur?

Answer 5

When two objects are touching each other. Like friction or air-resistance.

Question 6

When do non-contact forces act?

Answer 6

At a distance (without two objects touching), like gravitational force or magnetic force.

Question 7

when do opposite and equal force occur?

Answer 7

When an object exerts a force on another object.

Question 8

What causes gravity close to the earth?

Answer 8

The planet’s gravitational field strength.

Question 9

Weight is the force acting on an object due to…

Answer 9

Gravity.

Question 10

The weight of an object can be considered to act at the object’s…

Answer 10

Center of mass.

Question 11

The weight of an object can be measured using…

Answer 11

A calibrated spring balance (newtonmeter).

Question 12

What is the equation for weight?

Answer 12

Weight= mass (kg) X gravitational field strength (N/kg)

W= m g

Question 13

Weight and mass are … proportional to each other

Answer 13

Directly

Question 14

What can weight and mass be written as when together?

Answer 14

W = m

Question 15

True or false?
If two or more objects act on an object along the same line , their effect is the same as if they were replaced with a single resultant force.

Answer 15

True!

Question 16

The resultant force is the sum of … if they act in the same direction

Answer 16

The magnitudes of the forces

Question 17

The resultant force is the … between the magnitudes of the forces if they act in opposite directions.

Answer 17

Difference

Question 18

When are the forces said to be balanced?

Answer 18

When the resultant force on an object is zero

Question 19

Free body diagrams are used for what?

Answer 19

they use arrows to show all the forces acting on a single object.

Question 20

On a free body diagram, what does the arrow length represent?

Answer 20

The magnitudes of the force.

Question 21

On a free body diagram what does the direction of the arrow show?

Answer 21

The direction of the force.

Question 22

What can you use scale forces for?

Answer 22

They can be used to find the resultant of two forces which are not acting along the same line

Question 23

How do you use a scale drawing?

Answer 23

The forces are drawn end to end. The resultant can then be drawn between the two ends, forming a triangle.

Question 24

What is deformation?

Answer 24

A change in the shape of an object caused by stretching, squashing (compressing), bending, or twisting .

Question 25

How many forces have to act on a stationary object to deform it rather than make it move?

Answer 25

More than one.

Question 26

What is elastic deformation?

Answer 26

When the object can go back to it’s original shape and size when the forces are removed.

Question 27

What’s inelastic deformation?

Answer 27

When the object does not go back it’s original shape or size when forces are removed.

Question 28

What calculation is used to calculate spring constant?

Answer 28

Force applied (N) = spring constant (N/m) X extension

F = k e

Question 29

if a force that stretches or compresses an object does work on it, where will the energy be transferred to?

Answer 29

The object’s elastic potential store.

Question 30

What is the equation for elastic potential energy?

Answer 30

Elastic potential energy (J) = 1/2 X spring constant X (extension)^2 (m^2)

Ee = 1/2 k e^2

Question 31

A force or system of forces can cause an object to…

Answer 31

Rotate

Question 32

What is the turning effect of the force called?

Answer 32

The moment

Question 33

What’s the equation for a moment of a force?

Answer 33

Moment of a force (Nm) = force (N) X distance (m)

M = F d

Question 34

If an object is balanced, the sum of the clockwise moment equals…

Answer 34

The sum of the anticlockwise moments.

Question 35

What can lever and gears be used for?

Answer 35

To increase the moment of a force, making it easier to lift or rotate an object

Question 36

A lever allows a large moment of force to be produced by…

Answer 36

Allowing force to be applied further from the pivot.