# Tutorial Topic 5 ```1
5.8 Tutorial Topic 5
1.
A car of mass 900 kg turns into a corner with a tangential velocity of 25 m s -1 – the
corner has a radius of 100m. Calculate the force of friction between the tyres of the
2.
An object of mass 5 kg is moving in a circle with a radius 5 m at a tangential velocity
of 5 m s-1 calculate the following:
(a)
The centripetal force required to maintain this object in this circular path.
(b)
The centripetal acceleration experienced by the object as it rotates in this
circular path.
3.
If a person is spinning around with a heavy ball in their arms - the ball moves in a
circular path with radius 1.1m. The tangential velocity of the ball is 1.5 m s -1 and the
ball has a mass of 3 kg. Given all this information calculate the magnitude and
direction of the tension in the person’s arms.
4.
The radius of the Earth is 6380 km calculate the tangential velocity of a person
standing at the equator caused by the Earth’s rotation. Calculate the centripetal
acceleration of this person and express it as a fraction of the acceleration due to
gravity “g” – speculate on the danger of a person being thrown off the Earth’s
surface.
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5.
Neutron stars are the remains of supernovae; they are tiny – just a few km across –
and spin with an extremely large angular velocity. Suppose there is a neutron star of
radius 20 km spins with a period of 1.2 seconds. If an object is placed at the equator
of this star calculate the centripetal acceleration of this object and express it as a
multiple of the acceleration due to gravity on Earth – that is multiples of “g”.
6.
A large box is 4.2 m tall and 2.0 m wide with a coefficient of friction from box-to-floor
of 0.60. Calculate the maximum distance, from the floor, that a horizontal force must
be placed to slide the box without it rotating in the direction of motion.
7.
A cylindrical grinding wheel has a radius of 30 cm, a thickness of 8.0 cm and mass
of 20 kg determine its moment of inertia.
8.
A solid disc has a mass of 100 kg and a radius of 80 cm. The disc rotates around an
axis through its centre with an angular velocity of
9 rad s-1 determine its Kinetic
Energy.
9.
A 30 cm ruler rotates in a circle with the axis at one end. The ruler has an angular
velocity of 0.1 rad s-1 and mass of 100 g. An insect located on the axis moves to the
other end of the ruler. Determine the angular velocity of the ruler when the insect,
mass 3 g, reaches the far end of the ruler.
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10.