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10 questions
A skydiver of mass 80 kg falls vertically with a constant speed of 50 m s–1. The upward force acting on the skydiver is approximately
0 N.
80 N.
800 N.
4000 N.
A car of mass 1000 kg accelerates on a straight, flat, horizontal road with an acceleration
a = 0.3 m s–2.
The driving force F on the car is opposed by a resistive force of 500 N.
The net (resultant) force on the car is
200 N.
300 N.
500 N.
800 N.
A wooden block is sliding down an inclined plane at constant speed. The magnitude of the frictional force between the block and the plane is equal to
zero.
the magnitude of the weight of the block.
the magnitude of the component of weight of the block parallel to the plane.
the magnitude of the component of the normal reaction parallel to the plane.
Stephen pushes two boxes P and Q, that stay in contact, along a rough table, with a force F of 30 N.
Box P has a mass of 2.0 kg and box Q has a mass of 4.0 kg. Both boxes move with constant speed.
The resultant force on box Q is
0 N.
5.0 N.
15 N.
30 N.
A cart of mass M is on a horizontal frictionless table.
The cart is connected to an object of weight W via a pulley. Which of the following is the acceleration of the cart?
0
Two steel balls, of mass M and 2M, fall at constant speeds in a tube filled with oil.
Which of the following correctly compares the magnitudes of the net force and of the drag (resistance) force on the two balls?
A
B
C
D
A skydiver jumped out of an airplane. On reaching a terminal speed of 60 m s–1, she opened her parachute. Which of the following describes her motion after opening her parachute?
She went upwards for a short time, before falling to Earth at a speed of 60 m s–1.
She continued downwards at 60 m s–1, but hit the ground with less force.
She continued to fall but reached a new terminal speed of less than 60 m s–1.
She went upwards for a short time, before falling to Earth at a speed of less than 60 m s–1.
The diagram shows a girl attempting (but failing) to lift a heavy suitcase of weight W. The magnitude of the vertical upwards pull of the girl on the suitcase is P and the magnitude of the vertical reaction of the floor on the suitcase is R.
Which equation correctly relates W, P and R?
W = P + R
W > P + R
W < P + R
W = P = R
Objects A and B collide together. They end up joined together and stationary. During the collision, a force +F is exerted on object A by object B. According to Newton’s third law, there will also be a force of
–F acting on object B.
–F acting on object A.
+F acting on object B.
+F acting on object A.
A student is sitting on a chair. One force that is acting on the student is the pull of gravity. According to Newton’s third law, there must be another force which is
the upward push of the chair on the student.
the downward force on the student.
the downward push of the chair on Earth.
the upward force on Earth.
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