Chapter
13 - Forces and Motion Revision Questions
(For
problems requiring acceleration due to gravity take g = 9.8 m/s2)
- Define weight.
- What is the weight of a 15 kg dog? (Take
g = 9.8 m/s2)
- Find the weight of a 500g object.
- What is the downward force acting on
a 20 kg bike?
- A50 kg mass
is hanging by a rope from a beam. Are the forces balanced? Draw
the forces acting on the object. What is the tension in the rope?
- Define force. Give some examples of
contact and non-contact forces.
- Draw the forces acting a book that is
lying of a table.
- Draw the forces that are acting on a
car that is driving along a straight road at constant speed.
- State Newton’s three laws of motion.
- What is meant by Newton’s Law of
Universal Gravitation?
- Explain how displacement differs from
distance.
- Convert the
following to m/s (a) 36 km/h (b) 60 km/h (c) 108 km/h
- What unbalanced force is acting on an
object of mass 3.5kg experiencing an acceleration of 2 m/s2?
- Calculate the mass of an object that
is acted upon by a force of 250N and experiences an acceleration
of 5 m/s2.
- What acceleration results from a net
unbalanced force of 30 N on and object of 500g?
- A horizontal
force accelerates an 80kg bicycle and rider from rest to a velocity
of 4m/s in 2 seconds. Calculate the force required.
- An aircraft
accelerates from 75 m/s to 125 m/s in 10 s. if the engines produce
a thrust of 25 000N, what is the mass of the aircraft?
- A force of
500 N causes the velocity of a moving object of mass 250 kg to
increase in speed from 2 m/s to 8 m/s. How long does this take?
- Identify which of Newton’s Laws
apply to the following situations.
- Passengers lurch forward as a bus comes
to an abrupt halt.
- A fully laden bus accelerates more
slowly from rest than an empty bus.
- As the cannon ball is fired from the
cannon the cannon moves backwards.
- Explain the difference between inertia
and momentum.
- What is the relationship between momentum
and the mass and speed of an object?
- Describe the motion of an object attached
to a ticker tape that produces the following spread of dots.
(d) If the distance
between the first dot in (a) and the last dot is 10 cm., and the ticker
timer is operating at 50 Hz (50 dots/s, calculate the average velocity
of the object.
- Calculate the average speed of an object
that travels 200 km in 2 hr 30 min.
- Calculate the average velocity of a
plane that travels 400km East in a time of 1.5 hr.
- What distance is covered by a bike rider
cycling for 5 minutes at an average speed of 10m/s?
- How long does it take a motorcycle moving
at an average speed of 72 km/h to cover a distance of 500m?
- Calculate
the acceleration of a car that moves from rest to a velocity of
10 m/s in 5 seconds.
- A car moving
at 60 km/h brakes to halt in 3s. Calculate the average acceleration.
(Hint: don’t forget to convert km/h to m/s)
- An object
is thrown vertically upwards with a velocity of 12 m/s. How much
time does it take to reach the top of its flight? What is its
average velocity? How high does it rise?
- A child accidentally
drops a wooden block from an apartment window in a high-rise building.
What is its velocity after 3 s? If it takes 5s to hit the ground,
what is its velocity when it hits the ground? (Ignore air resistance).
Calculate the height of the window from which it was dropped.
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