P10- Forces and motion Flashcards Preview

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Flashcards in P10- Forces and motion Deck (17):
1

What is a scalar?

A scalar is any quantity that has magnitude, but not a direction associated with it. A scalar can be added and subtracted.

2

What is a vector?

A vector is any quantity that has both magnitude and direction. It id illustrated by drawing an arrow above the symbol that is used to convey direction and magnitude.

3

How do you add vector?

If two similar vectors point in the same direction add them, but if they are going in different directions subtract them.

4

Examples of scalar

Density, temperature, frequency, wavelength, pressure, power, potential difference.

5

Examples of vector

Magnitude field, velocity, force, momentum, current, acceleration, displacement

6

Define a force

A force can change the shape of an object or change its state of rest or its motion.

7

What do you measure forces in?

Newtons

8

When is the resultant force zero

When all forces are balanced. This means stationary objects remain stationary and moving objects keep on moving at the same speed and in the same direction.

9

What happens when the resultant force is not zero?

A stationary object begins to move in the direction of the resultant force and moving objects speed up, slow down or change direction.

10

How do you calculate a moment?

Moment= force x distance

11

A force of 50N is exerted on a claw hammer of length 30cm, calculate the moment

M=FxD
M=50x0.3
M=15nm

12

Moments of the force, can be increased by...

Increasing the size of the force.
Using a spanner with a longer handle.

13

What do gears do?

They multiply the turning effect of the engine force

14

What happens when a gear is in low gear?

The bigger the turning effect is

15

A gear wheel of radius 20mm is used to turn another gear wheel of radius 10mm with a force of 80N. Work out the moment of a force of a 10mm wheel.

Moment= force x gear wheel radius = 80N x 0.010m= 0.80Nm

16

How do you find the centre of mass on a flat object?

The centre of mass is along the axis of symmetry

17

How do you find the centre of mass of a suspended object?

If you suspend it and release it it would come to rest with its centre of mass directly below the point of suspension.