Our Dynamic Universe Part 1

Question 1

In the diagram shown, what force does the balance measure?

Answer 1

The balance will measure the reaction force (upwards).

Question 2

What is meant by an ‘inelastic collision’?

Answer 2

An inelastic collision is one in which not all kinetic energy is conserved.

(i.e. some of the kinetic energy is lost)

Question 3

Explain how you would resolve the vector shown into its horizontal and vertical components.

Answer 3

Use trigonometry (SOH CAH TOA):

F_horizontal = F cos 𝜃

F_vertical = F sin 𝜃

Question 4

What is impulse equivalent to?

Answer 4

Impulse is equivalent to change in momentum (of an object).

Question 5

State the principle of conservation of momentum.

Answer 5

In the absence of external forces, the total momentum before a collision (or explosion) is equal to the total momentum after a collision.

You must include every part of this explanation!

Question 6

Name the quantities shown in this formula.

Answer 6

W = weight

m = mass

g = gravitational field strength

Question 7

What is the unit for impulse?

Answer 7

The unit for impulse is newton seconds (N s).

Question 8

Explain how you would resolve the vector shown into its horizontal and vertical components.

Answer 8

Use trigonometry (SOH CAH TOA):

v_h = v cos 𝜃 = 14 cos 20º

v_v = v sin 𝜃 = 14 sin 20º

Question 9

Explain the launch of a space rocket from Earth’s surface, in terms of Newton’s Laws.

Answer 9

According to Newton’s 2nd Law (F = ma) an unbalanced force will result in an object accelerating. A rocket has thrust (up) and weight (down) and if these forces are unbalanced, the rocket will accelerate.

Question 10

What is meant by the term ‘impulse’?

Answer 10

Impulse is equal to force (on an object during a collision) multiplied by time (for the collision to take place).

Question 11

In the diagram shown, the forces are balanced.

Describe the motion of the lift, and explain what the reading on the balance will be.

Answer 11

The lift will either be stationary or moving at constant speed.

The reading on the balance will be equal to the weight.

Question 12

What is the unit for velocity?

Answer 12

The unit for velocity is metres per second (ms^-1).

Question 13

Name the quantities shown in this formula.

Answer 13

F = gravitational force

G = Universal Constant of Gravitation

m₁ = mass

m₂ = mass

r = distance between centre of masses

Question 14

Describe the motion of the object whose displacement, velocity and acceleration is shown in these graphs:

Answer 14

This object has a negative acceleration (its speed is decreasing).

Question 15

Describe the motion of the object whose displacement, velocity and acceleration is shown in these graphs:

Answer 15

This object is stationary.

Question 16

Here is a displacement-time graph for an object.

What would the corresponding velocity-time graph look like?

Answer 16

Question 17

Here is a displacement-time graph for an object.

What would the corresponding velocity-time graph look like?

Answer 17

Question 18

What is the unit for energy?

Answer 18

The unit for energy is joules (J).

Question 19

Describe the motion of the object whose displacement, velocity and acceleration is shown in these graphs:

Answer 19

This object is moving at steady / constant velocity.

Question 20

Explain, in terms of forces, an object moving with terminal velocity.

Answer 20

The forces are balanced and the object moves at a steady speed.

The balanced forces are weight and air resistance.

Question 21

Here is a velocity-time graph for an object.

What would the corresponding acceleration-time graph look like?

Answer 21

Question 22

Here is a displacement-time graph for an object.

What would the corresponding velocity-time graph look like?

Answer 22

Question 23

Describe the motion of the object whose displacement, velocity and acceleration is shown in these graphs:

Answer 23

This object has a positive acceleration (its velocity is increasing).

Question 24

Name the quantities shown in these formulas.

Answer 24

u = initial velocity

v = final velocity

t = time

s = displacement

a = acceleration

Question 25

Name the quantities shown in this formula.

Answer 25

F = force m = mass a = acceleration

Question 26

In the graph shown, what quantity can be found by calculating the **area under the graph**?

Answer 26

The area under a F-t graph is equal to the **impulse**.

Question 27

Here is a **velocity-time graph** for an object. What would the corresponding **acceleration-time graph** look like?

Answer 27

Question 28

Explain the motion of the skydiver, making reference to the **forces** acting.

Answer 28

The **weight (down)** is **greater** than the **air resistance (up)**. There is an **unbalanced force** acting on the skydiver. The skydiver will **accelerate** (speed up).

Question 29

What is the **unit** for **displacement**?

Answer 29

The **unit** for **displacement** is **metres** (**m**).

Question 30

Name the quantities shown in this formula.

Answer 30

F = force t = time m = mass v = final velocity u = initial velocity

Question 31

Name the quantities shown in this formula.

Answer 31

P = power E = energy t = time

Question 32

What is the **unit** for **force**?

Answer 32

The **unit** for **force** is **newtons** (**N**).

Question 33

What is the **unit** for **acceleration**?

Answer 33

The **unit** for **acceleration** is **metres per second *squared*** (**ms^-2**).

Question 34

Name the quantities shown in this formula.

Answer 34

p = momentum m = mass v = velocity

Question 35

What is meant by an **'elastic collision'**?

Answer 35

An elastic collision is one in which **all kinetic energy is conserved**.

Question 36

Here is a **displacement-time graph** for an object. What would the corresponding **velocity-time graph** look like?

Answer 36

Question 37

Here is a **velocity-time graph** for an object. What would the corresponding **acceleration-time graph** look like?

Answer 37

Question 38

What is the **unit** for **gravitational field strength**?

Answer 38

The **unit** for **gravitational field strength** is **newtons per kilogram** (**Nkg^-1**) OR metres per second squared (ms^-2).

Question 39

Two identical objects are dropped. One is dropped onto concrete. One is dropped onto a rubber mat. On the graph shown, which line represents the **concrete** and which line represents the **rubber mat**?

Answer 39

**A** is **concrete** **B** is **rubber mat**

Question 40

Here is a **velocity-time graph** for an object. What would the corresponding **acceleration-time graph** look like?

Answer 40

Question 41

The diagram shows the forces acting on a mass on a slope. How would the force parallel with the slope (*W_parallel *) be calculated?

Answer 41

The magnitude of the force parallel with the slope = **m g sin 𝜃**

Question 42

What is the **unit** for **momentum**?

Answer 42

The **unit** for **momentum** is **kilograms metres per second** (**kgms^-1**).

Question 43

What is the **unit** for **mass**?

Answer 43

The **unit** for **mass** is **kilograms** (**kg**).

Question 44

What effect does friction have on a moving object?

Answer 44

Friction will: - cause an object's speed to decrease - change some of the object's potential or kinetic energy into heat energy

Question 45

In the diagram shown, what is the value of the **unbalanced force**? What is the value of the **acceleration**?

Answer 45

The unbalanced force is 40 - 10 = **30N**. The acceleration, a = F/m = **1.5 ms^-2**.

Question 46

Name the quantities shown in this formula.

Answer 46

E_w = work done F = force d = distance

Question 47

Describe the motion of the skydiver, making reference to the **forces** acting.

Answer 47

The **weight (down)** is **equal to** the **air resistance (up)**. The **forces** acting on the skydiver are **balanced**. The skydiver will **move at a constant velocity**. (Although in Newton's First Law, balanced forces could mean constant speed OR stationary, in this case the skydiver *must* be moving at constant velocity or there would be no air resistance).

Question 48

Explain the motion of a spaceship floating through space, at steady speed, in terms of Newton's Laws.

Answer 48

Newton's 1st Law states that an object will stay at rest or move in a straight line at a steady speed if the forces acting on it are balanced.