Kognity Classwork Semester 1

A force of 24 N and a force of 15 N act at right angles to each other. The size of their resultant force is

• 15.8N

• 24.3N

• 28.3N

• 39.0N

A building has 5 floors. The windows on successive floors are separated by the same vertical distance. A brick is dropped from a window on each floor at the same time. The bricks should hit the ground at

• decreasing time intervals

• equal time intervals

• increasing time intervals

• the same time

The photograph shows a tennis ball being thrown vertically upwards.

Which row of the table shows the correct directions of the velocity and acceleration of the tennis ball while it is moving vertically upwards?

• A

• B

• C

• D

The photograph shows a tennis ball being thrown vertically upwards.

• A

• B

• C

• D

A point mass is moving in a horizontal circle with a velocity of constant magnitude v. At one particular time, the mass is at P. A short time later, the mass is at Q, as shown below.

Which vector diagram correctly shows the change in velocity, Δv, of the mass during this time?

• A

• B

• C

• D

A friction force f is acting on a block of weight w sliding down an incline at a constant speed. The force N is the normal reaction of the incline on the block. Which of the following free-body diagrams best represents the forces acting on the block?

• A

• B

• C

• D

A block is sliding down a rough slope. The force of sliding friction between the block and the slope depends on

• the speed of the block.

• the surface area of the block.

• the normal reaction between the block and the slope.

• the acceleration of the block.

A block is at rest on a rough incline as shown.

The frictional force acting on the block along the incline is

• zero.

• equal to the weight of the block.

• greater than the weight of the block.

• less than the weight of the block. 


A car collides with a more massive truck. 


During the collision, each vehicle exerts a force on the other. How do the magnitudes of these forces compare?

• The forces cannot be compared without knowing how the initial speeds compare.

• The magnitudes of the forces are equal.

• The force exerted by the truck is the greater.

• The force exerted by the car is the greater. 


Two unequal masses M and m are connected by a light cord passing over a pulley of negligible mass. When released, the system accelerates. 


Ignoring friction, which figure below best shows the correct free-body force diagrams for the two masses in the moving system?

• A

• B

• C

• D