Topic 1.2: Forces and Momentum Questions

State Newton's first law of motion.

State what is meant by the static friction force acting on an object.

A 2.5 kg block sliding on a frictionless surface speeds up from 3.0 m s⁻¹ to 11 m s⁻¹ along a straight line.

Calculate the impulse delivered to the block.

A cork floats at rest, partly submerged, on the surface of still water.

Identify the two forces acting on the cork and state the relationship between their magnitudes.

A 0.45 kg ball experiences a single net force of 6.0 N.

Calculate the magnitude of its acceleration.

A solid brass cylinder of volume 4.0 × 10⁻⁴ m³ is fully submerged in water of density 1.0 × 10³ kg m⁻³ (g = 9.8 N kg⁻¹).

Calculate the buoyancy force on the cylinder.

State the condition that must be met for the total momentum of a system of objects to be conserved during a collision.

State what is meant by the momentum of an object, and explain why momentum is a vector quantity.

State what is meant by an object being in translational equilibrium.

A single force of 200 N acts on a trolley at 52° above the horizontal.

Calculate the horizontal and vertical components of this force.

(cos 52° = 0.62, sin 52° = 0.79)

State Archimedes' principle.

State what is meant by the terminal velocity of an object falling through a fluid.

A 0.45 kg ball travelling at 14 m s⁻¹ is caught by a fielder and brought to rest in 0.060 s.

Determine the magnitude of the average force the fielder's hands exert on the ball.

A satellite moves in a circular orbit around a planet at a constant speed.

State the direction of the net force acting on the satellite, and state why the satellite is accelerating even though its speed does not change.

A small air bubble rises at a steady speed through a tall column of glycerol.

The upthrust on the bubble is 8.0 × 10⁻⁶ N and the weight of the air inside it is negligible.

Determine the viscous drag force on the bubble, and state its direction.

A cork cylinder of uniform cross-section floats upright in water with part of its length below the surface.

The cork has density ρ_c and the water has density ρ_w.

Show that the ratio of the submerged length to the total length of the cork equals ρ_c/ρ_w.

In a friction experiment, a block resting on a bench just begins to slide when a horizontal force of 15 N is applied.

The normal force on the block is measured to be 50 N.

Determine the coefficient of static friction between the block and the bench.

A skydiver jumps from a stationary balloon and falls through the air.

Describe how the magnitude of her acceleration changes from the instant she leaves the balloon until she reaches terminal velocity.

A 0.25 kg ball on a light string is swung in a vertical circle of radius 0.60 m.

At the lowest point of its path its speed is 5.0 m s⁻¹.

Calculate the tension in the string at that point, and explain why it is larger than the ball's weight.

(Take g = 9.8 m s⁻².)

A sealed plastic float of total volume 8.0 × 10⁻⁴ m³ and mass 0.32 kg is placed in fresh water (density 1.0 × 10³ kg m⁻³, g = 9.8 N kg⁻¹).

Show that it floats, then calculate the fraction of its volume that sits below the surface.