Physical Sciences - Trial Test

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Questions and Answers

Speed is a measure of the ______ at which an object moves over a distance.

rate

______ speed can be calculated by dividing the distance travelled by the time taken.

Average

Velocity is a measure of the rate of change in position. In order to describe the velocity fully, the ______ of the change in position must be stated.

direction

The ______ speed of an object is its speed at a particular instant of time.

instantaneous Signup and view all the answers

The ______ of an object moving in a straight line is a measure of the rate at which it changes speed.

acceleration Signup and view all the answers

The average acceleration of an object can be calculated by ______ the change in its speed by the time taken for change.

dividing Signup and view all the answers

An object will remain at rest, or will not change its speed or direction unless it is acted upon by an outside, ______ force.

unbalanced Signup and view all the answers

The acceleration of an object depends on the mass of the object and the ______ acting on it.

force Signup and view all the answers

When an object applies a force to a second object, the second object applies an and force to the first object.

equal and opposite Signup and view all the answers

All stored energy is called ______ energy.

potential Signup and view all the answers

The Law of Conservation of Energy states that energy is never created or ______.

destroyed Signup and view all the answers

A car travelling along a straight road has no forces acting on it.

False (B) Signup and view all the answers

Explain in terms of Newton's First Law of Motion why it is dangerous to have loose objects inside a moving car.

According to Newton's First Law of Motion, an object at rest will stay at rest, and an object in motion will stay in motion with the same velocity unless acted upon by a net force. When a car is in motion and suddenly brakes, passengers inside, due to inertia, will continue to move forward at the same velocity as the car before braking. This can lead to passengers colliding with objects inside the car or being thrown forward. Therefore, it is crucial to have secured loose objects inside a moving car. Signup and view all the answers

Newton's Second Law of Motion can be expressed as the formula F = ma. What quantities do each of the symbols in the formula represent?

F represents the net force acting on the object, m represents the mass of the object, and a represents the acceleration of the object. The equation states that the net force acting on an object is directly proportional to its mass and acceleration. Signup and view all the answers

A 1400 kg car accelerates at 3 m/s². What size force is needed to cause this acceleration?

The force needed to cause this acceleration is 4200 N, calculated using the formula F = ma. Therefore, F = 1400 kg * 3 m/s² = 4200 N. Signup and view all the answers

A force of 160 N causes an object to accelerate at 2 m/s². What is the object's mass?

The object's mass is 80 kg, calculated using the formula F = ma, where F = 160 N and a = 2 m/s². Therefore, 160 N / 2 m/s² = 80 kg. Signup and view all the answers

A force of 210 N acts on a mass of 70 kg. What is the acceleration?

The acceleration of the object is 3 m/s², calculated using the formula F = ma, where F = 210 N and m = 70 kg. Therefore, 210 N / 70 kg = 3 m/s². Signup and view all the answers

Classify the following as a type of potential energy or kinetic energy (use the letters K or P):

A bicyclist pedalling up a hill = P An archer with his bow drawn = P A volleyball player spiking a ball = K The wind blowing through your hair = K The chemical bonds in sugar = P A baseball thrown to second base = K Walking down the street = K Sitting in the top of a tree = P A bowling ball rolling down the alley = K A bowling ball sitting on the rack = P Signup and view all the answers

A baby carriage is sitting at the top of a hill that is 21 m high. The carriage with the baby has a mass of 1.5 kg. The carriage has ______ energy. Calculate it.

The carriage has potential energy. The potential energy of the carriage can be calculated using the formula PE = mgh, where m = 1.5 kg, g = 10 m/s², and h = 21 m. Therefore, PE = 1.5 kg * 10 m/s² * 21 m = 315 J. Signup and view all the answers

A car is traveling with a velocity of 40 m/s and has a mass of 1120 kg. The car has ______ energy. Calculate it.

The car has kinetic energy. The kinetic energy of the car can be calculated using the formula KE = 1/2 mv², where m = 1120 kg and v = 40 m/s. Therefore, KE = 1/2 * 1120 kg * (40 m/s)² = 896,000 J. Signup and view all the answers

A cinder block is sitting on a platform 20 m high. It weighs 7.9 kg. The block has ______ energy. Calculate it.

The block has potential energy. The potential energy of the block can be calculated using the formula PE = mgh, where m = 7.9 kg, g = 10 m/s², and h = 20 m. Therefore, PE = 7.9 kg * 10 m/s² * 20 m = 1580 J. Signup and view all the answers

A roller coaster is at the top of a 72 m hill and weighs 134 kg. The coaster (at this moment) has ______ energy. Calculate it.

The roller coaster has potential energy. The potential energy of the roller coaster can be calculated using the formula PE = mgh, where m = 134 kg, g = 10 m/s², and h = 72 m. Therefore, PE = 134 kg * 10 m/s² * 72 m = 96,480 J. Signup and view all the answers

Determine the kinetic energy of a 1000-kg roller coaster car that is moving with a speed of 20.0 m/s.

The kinetic energy of the roller coaster car can be calculated using the formula KE = 1/2 mv², where m = 1000 kg and v = 20.0 m/s. Therefore, KE = 1/2 * 1000 kg * (20.0 m/s)² = 200,000 J. Signup and view all the answers

If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy?

If the roller coaster car were moving with twice the speed, its kinetic energy would be four times greater than the original kinetic energy. This is because kinetic energy is proportional to the square of the velocity. Therefore, the new KE = 4 * 200,000 J = 800,000 J. Signup and view all the answers

The potential energy of a 40-kg cannon ball is 14000 J. How high was the cannon ball to have this much potential energy?

The height of the cannon ball can be calculated using the formula PE = mgh, where m = 40 kg, g = 10 m/s², and PE = 14000 J. Therefore, h = PE / (mg) = 14000 J / (40 kg * 10 m/s²) = 35 m. Signup and view all the answers

Which of the following statements about the Law of Conservation of Energy is TRUE? (Select all that apply)

Energy can be transformed from one form to another. (A), Energy can be neither created nor destroyed by ordinary means. (B), The total amount of energy in an isolated system is always constant, even before and after any energy transformations. (D) Signup and view all the answers

An object remains at rest, or will not change its speed or direction unless ______.

acted upon by an unbalanced force Signup and view all the answers

When an unbalanced force acts on an object, the of an object affects .

mass, acceleration Signup and view all the answers

For every action, there is ______.

an equal and opposite reaction Signup and view all the answers

Flashcards

Speed

A measure of how fast an object is moving over a distance.

Calculating average speed

Dividing the total distance traveled by the total time taken.