Unit 3: 2 - Using Physics to Make Things Work

Question 0

Give the equation to work out the size of a moment.

Answer 0

M = F x d

Moment (Nm) = Force (N) x perpendicular distance from the line of action of the force to the pivot (m).

Question 1

What is the turning effect of a force?

Answer 1

A moment.

Question 2

When using a lever, the force we are trying to move is called the ____, and the force we applied to the lever is called the ____.

Answer 2

When using a lever, the force we are trying to move is called the LOAD, and the force we applied to the lever is called the EFFORT.

Question 3

A lever acts as a ____, so the effort we apply can be much less than the load.

Answer 3

Force multiplier.

Question 4

What is the centre of mass?

Answer 4

The single point at which the mass appears to be concentrated.

Question 5

Any object that is freely suspended will come to rest with its centre of mass directly below the point of suspension. The object is then in _______.

Answer 5

Equilibrium

Question 6

What will happen to an object if the resultant moment is outside the base of the object?

Answer 6

The object will topple over.

Question 7

Give the equation for pressure.

Answer 7

P = F/A
Pressure (Pascals (Pa) or N/m^2) = Force (N)/The cross-sectional area at right angles to the direction of the force (m^2).

Question 8

Why are liquids used in hydraulics?

Answer 8

They are virtually incompressible and the pressure is transmitted equally in all directions.

Question 9

Give the 3 factors that effect the force exerted by a hydraulic pressure system depends on.

Answer 9

The force exerted by the system, the area of the cylinder of which this force acts on, and the area of the cylinder that exerts the force.

Question 10

The use of different cross-sectional areas on the effort and load sides of a hydraulic system means that it can be used as a…

Answer 10

Force multiplier.

Question 11

Why are force multipliers used?

Answer 11

So a small effort can move a large load.

Question 12

What is centripetal acceleration?

Answer 12

When an object moves in a circular motion and it constantly changes velocity, therefore accelerating.

Question 13

What will happen to an object if the centripetal force stops acting on it?

Answer 13

It will continue in a straight line at a tangent to the circle.

Question 14

Give the 3 factors which increase the centripetal force needed to make an object perform circular motion.

Answer 14

The mass of the object increases, the speed of the object increases and the radius of the circle increases.

Question 15

What type of motion is a pendulum swinging back and forth?

Answer 15

Oscillating motion.

Question 16

What does a simple pendulum consist of?

Answer 16

A mass, called a bob, suspended on the end of a length of string.

Question 17

What is the equilibrium position of a simple pendulum?

Answer 17

The position of the pendulum when it stops moving (the line of action of the centre of mass).

Question 18

What is the amplitude of a simple pendulum?

Answer 18

The distance between the equilibrium position and the highest position on either side.

Question 19

What is the time period of a simple pendulum?

Answer 19

The time taken for one complete cycle (either the time from the highest point to get back to the highest point, or the time taken for it to pass through equilibrium position in the same direction again).

Question 20

What is the only factor which affects the time period of a simple pendulum?

Answer 20

The length of the string.

Question 21

What is the frequency of oscillations?

Answer 21

The number of complete cycles in a second, measured in Hz.

Question 22

Give the equation that relates the time period and the frequency.

Answer 22

T = 1/f