PCFGStudy Combined Sci Trilogy Physics P2h

Question 1

Force A causes the bicycle to accelerate forwards. What name is given to force A?

Answer 1

friction

Question 2

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

Answer 2

• (the force on the pedal) causes a moment about the pedal axle
• which causes a force on the chain (which causes a moment about the rear axle)

Question 3

During the collision, the total momentum of the players is conserved. What is meant by ‘momentum is conserved’?

Answer 3

(total) momentum before = (total) momentum after

Question 4

The ice hockey players wear protective pads filled with foam. Explain how the protective pads help to reduce injury when the players collide.

Answer 4

• (protective pads) increase the time taken to stop (during the collision)
• so the rate of momentum decreases
• reducing the force (on the ice hockey player)

Question 5

What is inertia?

Answer 5

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

Question 6

Explain the motion of a skydiver, in terms of forces acting on the skydiver, from the moment the skydiver jumps from the plane 17,000 ft above the ground until they reach the ground.

Answer 6

• initially air resistance is less than gravity so the skydiver accelerates
• acceleration causes the air resistance to increase
• resultant force decreases to zero
• so the skydiver falls at terminal velocity
• the parachute is then deployed & air resistance is greater than weight so skydiver decelerates
• until terminal velocity is reached again and decelerates until diver reaches the ground

Question 7

State what happens to the frequency of the water wave as it passes into the slower region

Answer 7

nothing

Question 8

Give one use of ultraviolet

Answer 8

energy efficient lamps

Question 9

Electromagnetic waves are transverse. Some other types are longitudinal. Describe the difference between transverse & longitudinal waves.

Answer 9

• in a transverse wave, the oscillations are perpendicular to the direction of energy transfer
• in a longitudinal wave, the oscillations are parallel to the direction of energy transfer

Question 10

A teacher demonstrated how a magnetic field can cause a copper rod to accelerate. The teacher placed the copper rod on two brass rails in a magnetic field. The copper rod was able to move. The figure below shows the equipment used. The teacher closes the switch & the copper rod accelerates. Explain how Fleming’s left hand rule can be used to predict the direction in which the copper rod will move.

Answer 10

• hold thumb, first finger & second finger (of left hand) at right angles to each other
• second finger represents the current pointing out the paper
• first finger represents the field pointing downwards
• thumb points in the direction of the force
• (therefore) the rod moves from left to right

Question 11

Suggest two changes to the equipment that would increase the force on the copper rod

Answer 11

• decrease the resistance of the variable resistor
• use a stronger magnet