OCR A-Level Mechanics

Which of these are required for a system to be in equilibrium?

• No Net force

• Kinetic Energy to equal the GPE

• Moments to be balanced

• It to be stationary

• No forces to act on the system

Which of these statements about a stone dropped off a cliff is wrong?

• The stone's acceleration will decrease as it falls.

• The stone's speed increases

• The net force on the stone doesn't change

• The displacement of the stone keeps changing.

A couple is:

• 2 moments that cancel each other out

• 2 moments of the same magnitude

• 2 forces of the same size acting in opposite directions

• 2 forces acting in the same direction

2 objects of the same mass are placed in water. One floats and one sinks. Which one displaces more water?

• The sinking one

• The floating one

• Both the same

• Impossible to say

A material that does not yield is called:

• ductile

• plastic

• elastic

• brittle

Impulse is:

• Another name for a force

• The same as inertia

• A change in momentum

• always conserved

Tick all the vector quantities

• Mass

• Speed

• Acceleration

• Momentum

• Force

A cannon ball is fired directly upwards from the ground. Assuming no air resistance, which of these statements is wrong?

• At the peak of it's tranjectory its speed is 0m/s.

• It will hit the ground at the same speed it was fired upwards at.

• The force on it doesn't change.

• At the peak of its trajectory it isn't accelerating.