Kinematics, Dynamics, Work, Power, Energy

The distances between successive positions of a moving car, measured at equal time intervals, are shown. The car moves with

• acceleration that increases linearly with time.

• acceleration that increases non-linearly with time.

• constant speed.

• constant acceleration.

A sports car is accelerated from 0 to 100 km per hour in 3 s. What is the acceleration of the car?

• 0.1 g

• 0.3 g

• 0.9 g

• 3 g

A ball is tossed vertically upwards with a speed of 5.0 m s^–1. After how many seconds will the ball return to its initial position?

• 0.50 s

• 1.0 s

• 1.5 s

• 2.0 s

A projectile is fired horizontally from the top of a cliff. The projectile hits the ground 4 s later at a distance of 2 km from the base of the cliff. What is the height of the cliff?

• 40 m

• 80 m

• 120 m

• 160 m

An object of mass  is falling vertically through the air. The drag force acting on the object is . What is the best estimate of the acceleration of the object?

• Zero

• 2.5 m s^-2

• 7.5 m s^-2

• 10 m s^-2

A body is held in translational equilibrium by three coplanar forces of magnitude ,  and . Three statements about these forces are

I.  all forces are perpendicular to each other
            II.  the forces cannot act in the same direction
            III.  the vector sum of the forces is equal to zero.

Which statements are true?

• I and II only

• I and III only

• II and III only

• I, II and III

Child X throws a ball to child Y. The system consists of the ball, the children and the Earth. What is true for the system when the ball has been caught by Y?

• The momentum of child Y is equal and opposite to the momentum of child X.

• The speed of rotation of the Earth will have changed.

• The ball has no net momentum while it is in the air.

• The total momentum of the system has not changed.

A ball of mass m is thrown with an initial speed of u at an angle θ to the horizontal as shown. Q is the highest point of the motion. Air resistance is negligible. What is the momentum of the ball at Q?

• zero

• mu cosθ

• mu

• mu sinθ

An object has a weight of 6.10 × 10² N. What is the change in gravitational potential energy of the object when it moves through 8.0 m vertically?

• 5 kJ

• 4.9 kJ

• 4.88 kJ

• 4.880 kJ

An object of mass 1.0 kg hangs at rest from a spring. The spring has a negligible mass and the spring constant k is 20 N m⁻¹. What is the elastic potential energy stored in the spring

• 1.0 J

• 2.5 J

• 5.0 J

• 10 J