Forces and Motion
A 10 kg object is pulled with a force of 50 N.
What is its acceleration (ignore friction)?
A. 2 m/s²
B. 5 m/s²
C. 10 m/s²
D. 500 m/s²
B. (a = F / m = 50 / 10 = 5 m/s²)
A car travels 100 m in 5 seconds.
a. Find its average speed.
b. If it continues at the same speed, how far will it go in 20 seconds?
a. 100 ÷ 5 = 20 m/s
b. 20 × 20 = 400 m
A ramp (inclined plane) 4 m long is used to raise a box 1 m high.
What is the mechanical advantage of the ramp?
A. 1
B. 2
C. 3
D. 4
D (M.A. = Length / Height = 4 / 1 = 4)
When a person lifts a book, what are the main energy transformations?
Chemical energy in muscles → Kinetic energy of arms → Gravitational potential energy in the book
A rock has a mass of 800 g and displaces 320 cm³ of water.
a. Calculate its density.
b. Will it float or sink in water (density = 1 g/cm³)?
a. 800 ÷ 320 = 2.5 g/cm³
b. It will sink (since 2.5 > 1)
A car moves at constant velocity along a straight road.
Which statement is true about the forces acting on it?
A. The forward force is greater than friction
B. The forward force equals friction
C. The forward force is less than friction
D. There is no friction
B. The forward force equals friction
A bus increases its speed from 8 m/s to 20 m/s in 6 seconds. Find its acceleration.
(20 − 8) ÷ 6 = 2 m/s²
A pulley system helps lift a load with an effort of 50 N.
If the load lifted is 150 N, what is the mechanical advantage?
A. 1
B. 2
C. 3
D. 4
C (M.A. = 150 / 50 = 3)
A hydroelectric plant converts 5,000 J of gravitational potential energy into 4,000 J of electrical energy.
What is the efficiency of the plant?
80%
Explain why ice floats on water even though it is made of the same substance.
Because ice is less dense than water — the water molecules in ice are arranged farther apart in a crystal structure.
Which situation best shows Newton’s First Law of Motion?
A. A ball speeding up on a slope
B. A car accelerating on a highway
C. A book remaining at rest on a table
D. A rocket launching upward
C. A book remaining at rest on a tableB. A net force acts on it
A car moving at 30 m/s comes to a stop in 10 seconds.
Find its acceleration.
a = (0 − 30) ÷ 10 = −3 m/s² (deceleration)
A wheel and axle has a wheel radius of 20 cm and an axle radius of 5 cm.
Find its mechanical advantage.
A. 2
B. 3
C. 4
D. 5
D (M.A. = Radius of wheel / Radius of axle = 20 / 5 = 4)
A roller coaster car at the top of the track has 10,000 J of potential energy.
At the bottom, it has 9,500 J of kinetic energy.
Explain what happened to the missing 500 J.
It was transformed into heat and sound energy due to friction and air resistance.
Describe the particle arrangement and movement in solids, liquids, and gases.
Solid: tightly packed, vibrate in fixed positions
Liquid: close together but can slide past each other
Gas: far apart, move freely and quickly
When you push a wall and the wall pushes back with equal force, it shows:
A. Newton’s 1st Law
B. Newton’s 2nd Law
C. Newton’s 3rd Law
D. The Law of Gravity
C. Newton’s 3rd Law
A cyclist moves at constant speed around a circle. Which statement is true?
A. Speed and velocity are constant
B. Speed changes, velocity stays the same
C. Velocity changes, speed stays the same
D. Both speed and velocity change
C. Velocity changes, speed stays the same
A lever is used to lift a load of 60 N using an effort of 20 N. What is the mechanical advantage of the lever?
B (M.A. = Load / Effort = 60 / 20 = 3)
A light bulb converts 60 J of electrical energy into 48 J of light and 12 J of heat energy.
What is its efficiency for producing light?
80%
A cube of aluminum (density = 2.7 g/cm³) and a cube of iron (density = 7.9 g/cm³) have the same volume.
Which statement is true?
A. The aluminum cube has more mass
B. Both cubes have the same mass
C. The iron cube has more mass
D. They have equal densities
C. The iron cube has more mass
A car slows down because of:
A. Inertia
B. Gravity
C. Friction
D. Acceleration
C. Friction
A student runs 100 meters north in 20 seconds, then 100 meters south in 20 seconds.
a. What is the total distance?
b. What is the total displacement?
c. What is the average velocity?
a. 200 m
b. 0 m (returns to start)
c. 0 m/s (no net displacement)
In a pulley system, if the effort distance is doubled, the effort force is:
A. Halved
B. Doubled
C. Unchanged
D. Zero
A. Halved
Describe the energy transformations that occur when you strike a match.
Chemical energy → Heat energy → Light energy
The amount of matter in an object is its:
A. Weight
B. Volume
C. Density
D. Mass
D. Mass