1.If an object has a constant speed, then its velocity must also be constant.
2.The inertia of an object is relatively constant, but an object’s momentum can be changed.
3.A high jumper clearing a 2.20 m bar experiences the same level of pain landing on a concrete apron as he does when landing on an 0.75 m air cushion placed on the concrete.
4.If a ball is allowed to drop from the top of a cliff, both its potential energy and kinetic energy will each have the same value when it has fallen 10 m from the cliff top as when it has fallen 20 m from the cliff top.
5.If a child swings a ball held by a piece of string in a horizontal circular path above her head, then when the string breaks the ball will fly outwards along the line of the string.
6.The density of a liquid held in a container does not affect the pressure exerted by the liquid at any given (variable) depth within the container.
7.A metal bar and a similar mass of water are supplied with the same amount of external heat. The temperature of the water will rise much more than that of the metal bar.
8.Two railway carriages are involved in an inelastic collision. The first has a mass of 1000.0 kg and is moving at 40.0 m/s and the second has a mass of 1200.0 kg and is moving along the track in the same direction at 10.0 m/s. What is the resultant speed of the two coupled carriages after the collision.
9.a)What is the instantaneous velocity of a freely falling object 10.0 seconds after it
is released from a position of rest at the top of a tall building. Ignore air resistance.
b)What is the average velocity during this 10.0 second time interval.
c)How far will it fall during this time.
10.What is the speed over the ground, of an aircraft flying at 200km/hr relative to the air caught in a 20 km/hr head wind (i.e. the wind is directly against the plane).
11.The string in Question 4 is 2.00 m long and the angular velocity is 4.00 radians per second. The mass of the ball is 0.500 kg. What is the tension in the string.
12.Alex is hauling a load of cement bags using a pulley system from the ground to the third level at a building site. The total mass of the bags is 200.0 kg, but the pulley system gives him a Mechanical Advantage of 10.00. If he lifts the load a vertical distance of 20.00 m in 15.00 seconds, what power is he delivering.
13.A fixed mass of a gas is held in an adjustable sealed container at a pressure of 100.0 kPa, the initial volume is 3.00 m3. If the container size is decreased to 0.750 m3, what will the final pressure of the gas inside be? Assume that the temperature remains constant.
14.A ball is thrown from the top of a building 50.0 m high with an initial velocity of 20.0 m/s directly upward (i.e. vertically). Assume that as it falls it just misses the building and carries on down to ground level, rather than hitting the thrower on the head! Calculate:
a) The time taken for the ball to reach is maximum height.
b)The value of this maximum height.
c)The velocity of the ball just as it passes the thrower on the way down? Ignore any air resistance
d)The velocity of the ball just as it hits the ground.
15.A boat is crossing a river. It heads off due north with a velocity of 10.0 km/h relative to the water, perpendicular to the bank. The river is flowing with a uniform current of 5.00 km/h due east. Calculate:
a)The velocity of the boat relative to a stationary observer on the riverbank.
b)The direction of the boat as seen by the observer, given with respect to north.
c)The time taken in minutes for the boat to cross the river, if it is 500 m wide
16.A small sphere of mass m kg hangs by a thin rope from the roof of a train carriage (like a pendulum say). The train moves off from the platform with a constant acceleration of ‘a’ m/s2 This causes the sphere to effectively swing backwards and adopt a position with the rope at angle theta (q) to the vertical. It stays in this position due to constant acceleration. By invoking Newton’s second law:
a) derive an expression for the acceleration of the train. Hint: consider the horizontal and vertical components of the tension force in the rope, your expression will be in terms of the acceleration ‘a’ and the gravitational acceleration g (10.0 m/s2), and the angle q.
b)If the angle q is 30.00 calculate the acceleration of the train.
c)If the mass of the sphere is 2.00 kg calculate the tension in the rope.
17.A horizontal Venturi meter is used to measure the flow rate of water in 150 mm diameter water mains. The throat diameter of the meter is 75.0 mm. The pressure in the mains is measured as 3050 kPa and the pressure in the throat is 50.0 kPa, the density of water is 1000.0 kg/m3 . Use Bernoulli’s Principle to:
a)Determine the velocity of flow in the throat.
b)Hence determine the flow rate in the water mains.