Unit 301 NL L3-L7, Mat L1-L4

A block of steel requires a force of 15N applied parallel to a steel plate to keep it moving with constant velocity across the plate. If the normal force between the block and the plate is 30N, determine the dynamic coefficient of friction.

• 0.5

• 2

• 450

• 45

The material of a brake is being tested and it is found that the dynamic coefficient of friction between the material and the steel is 0.5. Calculate the normal force when the friction force is 500N

• 0.250N

• 2500N

• 1000N

• 250N

When referring to heat energy. What is Absolute Zero referring to?

• It is the point where elements freeze

• It is the point where water freezes

• It is the pointe where all molecular motion stops

• It is the point where all atom motion stops. ​

What is the difference between heat and temperature?

• Heat is a measure of temperature

• Heat and temperature both measure energy

• Heat is a measure of thermal energy and temperature is a measure of heat

• Heat is the same as temperature

What temperature does water boil at?

Which of the following statements best defines centripetal acceleration?

• The acceleration of an object towards the centre of a circle when an object is in rotating motion around a circle at constant speed

• The acceleration of an object away from the centre of a circle when the object is in rotating motion around a circular path at an increasing velocity

• The centripetal accelerationof an object is the resultant force on the object moving in a circle towards the centre of the circle

• The centripetal acceleration of an object is the resultant force acting on the object moving in a circle perpendicularly to the radius

The blade of a lawnmower rotates at frequency of 50 revolutions per second (50Hz). What is the angular velocity of the blade in rad/sec?

A bucket of mass of 8kg is filled with water and attached to a rope with a length of 0.9m. What is the minimum angular velocity the bucket must have at the top of its rotation path so no water spills out? Use g=10m/s²

• 8,49m/s

• 81m/s

• 9m/s

• 3m/s