forces exam question

Question 1

describe how the force on the pedal causes a moment about the rear axle (2)

Answer 1

-force on the pedal causes a moment about the pedal axle
-which causes a force on the chain

Question 1

Describe how the force on the pedal causes a moment about the rear axle

Answer 1

-force on the pedal caused a moment about the pedal axle
-which causes a force on the chain

Question 2

What is inertia?

Answer 2

The tendency of an object to continue in its state of rest or motion

Question 3

Explain why and egg is less likely to break when dropped onto soft foam rather than onto concrete floor (3)

Answer 3

-soft foam increases time taken to stop
-decreases the rate of change in momentum
-reducing force on egg

Question 4

Explain the changin motion of the skydiver in terms of the forces acting on the skydiver after jumping (4)

Answer 4

-initially air resistance is less than weight
-acceleration causes air resistance to increase
-resultant force decreases to 0
-so skydiver falls at terminal velocity

Question 5

Jumping from 39000m allowed a skydiver to reach a much higher speed than a skydiver jumping from 4000m. Explain why (3)

Answer 5

-the higher the altitude, the less dense the air
-so the air resistance on the skydiver was less
-so the sky diver was able to accelerate longer before reaching terminal velocity

Question 6

An aircraft window is shaped like an inward C. Explain why the window has been designed to have this shape (2)

Answer 6

-force from air pressure acting from inside to outside bigger than force acting inwards
-so keeps the window in position

Question 7

in the extension of a spring practical, describe one technique that you could have used to improve the accuracy of the measurements taken by the student (2)

Answer 7

use a set square to line up the bottom of the spring with the ruler scale

Question 8

in the extension of the spring practical, explain why adjusting the ruler to make it vertical is important (2)

Answer 8

to reduce the error in measuring the extension of the spring
as the ruler at an angle would make the measured extensions shorter

Question 9

why does a spring not follow direct proportionality after a while? (2)

Answer 9

-the spring has been elastically deformed
-because it went past its limit of proportionality

Question 10

there are places on a journey where the train accelerates without changing speed. explain how this can happen (2)

Answer 10

train changes direction so velocity changes
acceleration is the rate of change of velocity

Question 11

what is meant by the braking distance of a vehicle? (1)

Answer 11

the distance travelled under the braking force

Question 12

explain why the stopping distance of a car increases if the driver is tired (2)

Answer 12

the reaction time increases
so the thinking distance will increase

Question 13

a ramp is lowered by pulling on the rope or by pulling on the handle. a hinge acts as a pivot. explain why it is easier to lower the ramp by pulling on the rope rather than pulling on the handle (2)

Answer 13

-the perpendicular distance from the hinge to the line of action of the force is greater
-so a smaller force is required

Question 14

the further a swimmer dives below the surface of the sea, the greater the pressure on the swimmer. explain why. (2)

Answer 14

-increasing the depth, increases the height of the water above the swimmer
-which increases the force of the water acting on the swimmer