Download Grade 11 Physics – Homework 5 1. A skydiver of mass 80 kg falls

Grade 11 Physics – Homework 5
1.
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
A.
0 N.
B.
80 N.
C.
800 N.
D.
4000 N.
(Total 1 mark)
2.
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
A.
200 N.
B.
300 N.
C.
500 N.
D.
800 N.
(Total 1 mark)
3.
Which of the following is the condition for a body to be in translational equilibrium?
A.
The resultant force on the body in any direction is zero.
B.
The velocity of the body in any direction is zero.
C.
No external force is acting on the body.
D.
No work is done on the body.
(Total 1 mark)
4.
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
A.
zero.
B.
the magnitude of the weight of the block.
C.
the magnitude of the component of weight of the block parallel to the plane.
D.
the magnitude of the component of the normal reaction parallel to the plane.
(Total 1 mark)
5.
Which of the following is a correct statement of Newton’s second law of motion?
A.
A force acting on a body is proportional to the mass of the body.
B.
The rate of change of momentum of a body is equal to the net external force acting on the body.
C.
The momentum of a body is proportional to the net external force acting on the body.
D.
A force acting on a body is proportional to the acceleration of the body.
(Total 1 mark)
1
6.
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
A.
0 N.
B.
5.0 N.
C.
15 N.
D.
30 N.
(Total 1 mark)
7.
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?
M
A.
W
g
W
B.
W
W
M
g
C.
Mg
W
D.
0
(Total 1 mark)
8.
A net force of magnitude 4.0 N acts on a body of mass 3.0 kg for 6.0 s. The body is initially at rest. Which
of the following is the speed of the body after the 6.0 s interval?
A.
0.50 m s–1
B.
2.0 m s–1
C.
4.5 m s–1
D.
8.0 m s–1
(Total 1 mark)
2
9.
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?
Net force
Drag force
A.
same
same
B.
same
different
C.
different
same
D.
different
Different
(Total 1 mark)
10.
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?
A.
She went upwards for a short time, before falling to Earth at a speed of 60 m s–1.
B.
She continued downwards at 60 m s–1, but hit the ground with less force.
C.
She continued to fall but reached a new terminal speed of less than 60 m s–1.
D.
She went upwards for a short time, before falling to Earth at a speed of less than 60 m s–1.
(Total 1 mark)
11.
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?
A.
W=P+R
B.
W>P+R
C.
W<P+R
D.
W=P=R
(Total 1 mark)
12.
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
A.
the upward push of the chair on the student.
B.
the downward force on the student.
C.
the downward push of the chair on Earth.
D.
the upward force on Earth.
(Total 1 mark)
3
13.
A lamp of weight W is suspended by a wire fixed to the ceiling. With reference to Newton’s third law of
motion, the force that is equal and opposite to W is the
A.
tension in the wire.
B.
force applied by the ceiling.
C.
force exerted by the lamp on the Earth.
D.
force exerted by the Earth on the lamp.
(Total 1 mark)
14.
If a moving object is subject to a constant force, which of the following can be correctly deduced from
Newton’s first law?
A.
The object continues to move with a changing velocity.
B.
The object continues to move with a constant velocity.
C.
The object continues to move with a changing direction.
D.
The object continues to move in the same direction.
(Total 1 mark)
15.
Mandy stands on a weighing scale inside a lift (elevator) that accelerates vertically upwards as shown in the
diagram below. The forces on Mandy are her weight W and the reaction force from the scale R.
The reading of the scale is
A.
R + W.
B.
W.
C.
R.
D.
R – W.
(Total 1 mark)
16.
The radius of a circle is
with their uncertainties. (4 marks)
. Determine the area and circumference of the circle, along
17.
A square has sides of length
uncertainties. (4 marks)
18.
A car experiences a force of
and has a mass of
acceleration of the car, along with the uncertainty in that value. (2 marks)
19.
A feather falls through a vacuum on the surface of Earth for
distance traveled, along with the uncertainty in that value (3 points)
. Determine the area and perimeter, along with their
Determine the
. Determine the
4