GRADE 8 PHYSICS - FORCES, MASS, WEIGHT, ENERGY, AND POWER
Answer the following question below
correctly with a cross (X) in a box on your answer sheet.
1.
Quantity which has same unit are…
a. force and power
b. force and weight
c. mass and weight
d. mass and density
2.
Which object has the largest resultant force?
3.
An object of mass 2 kg is pushed along a horizontal flat
surface. The friction force is measured to be 4 N. When the same object is
pushed along the same surface with a force of 10 N, it moves with a
acceleration….
a.
2 m/s2 b. 3 m/s2 c. 4 m/s2 d. 5 m/s2
4.
What is the
acceleration of the box below.
a. 1.0 m/s2 b. 1.5 m/s2
c. 2.0 m/s2 d. 2.5 m/s2
5.
The table below
shows the weight of some of the mass of the object on the surface of four
different planet. Which planet has the greatest gravitational acceleration?
|
|
mass
|
weight
|
|
a.
b.
c.
d.
|
0.5
kg
2.0
kg
0.5
kg
2.0
kg
|
20
N
20
N
40
N
40
N
|
(Singapore O Level Test, 2004)
6. The table shows
the results of a class experiment to measure the Potential Energy on some
Planets. An astronaut drops a ball with mass 50 kg and height ball from ground
on each Planet is 20 meter. Which Planet produces the most Potential Energy?
|
|
Name
|
Gravity
(m/s2)
|
|
a
|
Earth
|
9,80
|
|
b
|
Mars
|
3,78
|
|
c
|
Neptune
|
8,89
|
|
d
|
Saturn
|
9,16
|
7. A student uses a newton meter to
pull an object horizontally along rough ground. The student multiplies the
newton meter reading by the distance moved by the object.
What does this calculation give?
a. the efficiency of the process
b. the kinetic energy of the
object
c. the power generated
d. the work done on the object
8. A man of mass 50 kg jumps to a height of 1 m. His potential
energy at the highest point is…. (g = 10 m/s2)
a.
50 J b. 60
J c. 500 J d. 600 J
9.
Figure below shows a rock that is falling from the top of
a cliff into the river.
The
mass of the rock is 50 kg. And the acceleration due to gravity is 10 ms-2.
The rock falls from rest through a distance of 100 meter before it hits the river.
The potential energy of the rock is….
a.
500000 J
b.
50000 J
c.
5000 J
d. 500
J
10. An object travel with velocity 5
m/s and has 500 J of kinetic energy.
What
is the mass of the object?
a.
10 kg b. 20
kg c. 30 kg d. 40 kg
11. Three objects K, L, and M have
different masses and different velocities as shown in the table.
|
|
mass
(kg)
|
velocity
(m/s)
|
|
K
L
M
|
1
2
5
|
3
2
1
|
What is
the order of increasing kinetic energy (smallest first) of the objects?
a. K à L à M b.
K à M à L
c. M à L à K d.
M à K à L
12. A 300 N is applied to a box to
move it up a ramp, as shown.
How much work done by the force when moving the box
from X to Y?
a. 900 J
b. 1200 J
c. 1350 J
d. 1500 J
13. Look at the picture below.
A
man is sliding on the slippery road with a height 15 meter to the ground.
Calculate the work done by the man if the man with a
mass 60 kg and acceleration due to gravity is 10 m/s2.
a. 900 J
b. 9000 J
c. 90 000 J
d. 900 000 J
14. A crane lifts a load of 6000 N
through a vertical distance of 15 meter in 30 seconds.
What
is the Power during this operation?
a.
200 W b. 400 W c. 3000 W d. 12 000 W
15. A students with a weight of 450 N runs up the flight of
stairs shown in diagram below in 5 seconds. The student’s Power is….
a. 90 W
b. 900 W
c. 1250 W
d. 12500 W
Komentar
Posting Komentar