Topic 1 Mechanics

A glider is descending at constant speed at an angle of 15° to the horizontal. The diagram shows the directions of the lift L, air resistance R and weight W acting on the glider.
Which vector triangle could represent the forces acting on the glider?

A pendulum bob is held stationary by a horizontal force H. The three forces acting on the bob are shown in the diagram.
The tension in the string of the pendulum is T. The weight of the pendulum bob is W.
Which statement is correct?

• A H = T cos 30°

• B T = H sin 30°

• C W = T cos 30°

• D W = T sin 30°

One object moves directly from P to R.
In a shorter time, a second object moves from P to Q to R.
Which statement about the two objects is correct for the journey from P to R?

• A They have the same average speed.

• B They have the same average velocity.

• C They have the same displacement.

• D They travel the same distance.

The graph shows how velocity v varies with time t for a bungee jumper.
At which point is the bungee jumper momentarily at rest and at which point does she have zero acceleration?

• A Jumper at rest at Q; jumper with zero acceleration at P

• A Jumper at rest at Q; jumper with zero acceleration at R

• A Jumper at rest at R; jumper with zero acceleration at Q

• A Jumper at rest at R; jumper with zero acceleration at R

An archer draws his bowstring back to position X. The bowstring and arrow are shown. The tension T in the string is also shown. Then he draws the bowstring back further to position Y.
The resultant force on the arrow is greater when the arrow is released from position Y.
What is the increase in force?

• A 15 N

• B 27 N

• C 40 N

• D 53 N

A uniform metre rule of weight 2.0 N is pivoted at the 60 cm mark. A 4.0 N weight is suspended from one end, causing the rule to rotate about the pivot.
At the instant when the rule is horizontal, what is the resultant turning moment about the pivot?

• A zero

• B 1.4 N m

• C 1.6 N m

• D 1.8 N m

The diagram shows a barrel of weight 1.0 × 10^3 N on a frictionless slope inclined at 30o to the horizontal.
A force is applied to the barrel to move it up the slope at constant speed. The force is parallel to the slope.
What is the work done in moving the barrel a distance of 5.0 m up the slope?

• A 2.5 × 10^3 J

• B 4.3 × 10^3 J

• C 5.0 × 10^3 J

• D 1.0 × 10^4 J

The diagram shows two vectors X and Y.
In which vector triangle does the vector Z show the magnitude and direction of vector X – Y?

A stone is thrown upwards from the top of a cliff. After reaching its maximum height, it falls past the cliff-top and into the sea.
The graph shows how the vertical velocity v of the stone varies with time t after being thrown upwards. R and S are the magnitudes of the areas of the two triangles.
What is the height of the cliff-top above the sea?

• A R

• B S

• C R + S

• D R - S

A wooden block of mass 0.60 kg is on a rough horizontal surface. A force of 12 N is applied to the block and it accelerates at 4.0 m s^–2.
What is the magnitude of the frictional force acting on the block?

• A 2.4 N

• B 9.6 N

• C 14 N

• D 16 N

The vector diagram shows three coplanar forces acting on an object at P.
The magnitude of the resultant of these three forces is 1 N.
What is the direction of this resultant?

A trolley runs from P to Q along a track. At Q its potential energy is 50 kJ less than at P.
At P, the kinetic energy of the trolley is 5 kJ. Between P and Q the work the trolley does against friction is 10 kJ.
What is the kinetic energy of the trolley at Q?

• A 35 kJ

• B 45 kJ

• C 55 kJ

• D 65 kJ

The graph shows how the acceleration of an object moving in a straight line varies with time.
The object starts from rest.
Which graph shows the variation with time of the velocity of the object over the same time interval?

The graph shows how the momentum of a motorcycle changes with time.
What is the resultant force on the motorcycle?

• A 50 N

• B 500 N

• C 2500 N

• D 5000 N

The diagrams show two ways of hanging the same picture.
In both cases, a string is attached to the same points on the picture and looped symmetrically over a nail in a wall. The forces shown are those that act on the nail.
In diagram 1, the string loop is shorter than in diagram 2.
Which information about the magnitude of the forces is correct?

• A R1 = R2; T1 = T2

• B R1 = R2; T1 > T2

• C R1 >R2 ; T1 < T2

• D R1 < R2; T1 = T2

A weight W hangs from a trolley that runs along a rail. The trolley moves horizontally through a distance p and simultaneously raises the weight through a height q.
As a result, the weight moves through a distance r from X to Y. It starts and finishes at rest.
How much work is done on the weight during this process?

• A Wp

• B W(p + q)

• C Wq

• D Wr

The graph is a load-extension graph for a wire undergoing elastic deformation.
How much work is done on the wire to increase the extension from 10 mm to 20 mm?

• A 0.028 J

• B 0.184 J

• C 0.28 J

• D 0.37 J

A radio-controlled toy car travels along a straight line for a time of 15 s.
The variation with time t of the velocity v of the car is shown below.
What is the average velocity of the toy car for the journey shown by the graph?

• A –1.5 m s^–1

• B 0.0 m s^–1

• C 4.0 m s^–1

• D 4.5 m s^–1