Beath High School - Int 1 Physics1 Intermediate 1 Physics Movement Forces Speed and acceleration Moving bodies

Beath High School - Int 1 Physics2 Intermediate 1 Physics Movement Forces

Beath High School - Int 1 Physics3 The unit of force is the n _ _ _ _ _, symbol N. Forces can be measured using a n _ _ _ _ _ balance. When a force acts on a spring balance, the spring inside it s _ _ _ _ _ _ _ _. The position of the stretched spring on the s _ _ _ _ tells you the size of the force. n e w t o n s t r e t c h e s s c a l e Measuring force n e w t o n

Beath High School - Int 1 Physics4 A newton balance is used to measure f _ _ _ _. f o r c e Weight _ _ newtons 1 0

Beath High School - Int 1 Physics5 Weight is a f _ _ _ _. f o r c e Weight Weight is the pull of the Earth on an object due to g _ _ _ _ _ _. A 1 kilogram mass (1 kg) has a w _ _ _ _ _ of 10 newtons (10 N). This means the earth p _ _ _ _ the 1 kilogram mass with a force of 10 newtons. g r a v i t y w e i g h t p u l l s

Beath High School - Int 1 Physics6 For any object we can find its weight if we know the mass of the object in kilograms. Calculating weight weight = 10 x mass (N) (kg) newtons kilograms

Beath High School - Int 1 Physics7 example 1: Find the weight of a 2 kg bag of sugar. Calculating weight weight = 10 x mass = 10 x = N 2 20 The weight of a 2 kg bag of sugar is N 20

Beath High School - Int 1 Physics8 example 2: Find the weight of a 55 kg pupil. Calculating weight weight = 10 x mass = 10 x = 550 N 55 The weight of a 55 kg pupil is 550 N

Beath High School - Int 1 Physics9 Friction is a force that opposes the m _ _ _ _ _ of a body. Friction m o t i o n The force of friction can s _ _ _ a moving object or s _ _ _ it down. s t o p s l o w The force of friction can also keep objects from starting to m _ _ _. m o v e

Beath High School - Int 1 Physics10 F _ _ _ _ _ _ _ is caused by the contact of two surfaces. Friction If objects do not slide across each other easily, the force of friction between the surfaces of two objects is l _ _ _ _. l a r g e If the objects slide e _ _ _ _ _, the force of friction is small. e a s i l y

Beath High School - Int 1 Physics11 H _ _ _ Friction Sliding rough surfaces is like sliding the bristles of two brushes - it is difficult. L _ _ Friction Sliding smooth surfaces is like sliding the backs of two brushes - it is easy. When the force of friction between surfaces is h _ _ _, we say they are rough, when the force of friction is low, we say they are s _ _ _ _ _. Friction h i g h H i g h L o w s m o o t h

Beath High School - Int 1 Physics12 The force of friction can be increased by making the surfaces r _ _ _ _ _ _ or by pressing the surfaces h _ _ _ _ _ together. Changing Friction r o u g h e r h a r d e r The force of friction can be reduced by making the surfaces s _ _ _ _ _ _ _ or lifting the surfaces away from each other. s m o o t h e r Lubrication for example, uses o _ _ which lifts two surfaces apart and r _ _ _ _ _ _ the force of friction. o i l r e d u c e s Air can also be used to lift surfaces apart e.g. in the h _ _ _ _ _ _ _ _ _. h o v e r c r a f t

Beath High School - Int 1 Physics13 When an object moves through the air, the air rubs against the object causing friction; this air friction is called air r _ _ _ _ _ _ _ _ _. Streamlining r e s i s t a n c e Streamlining is when you change the shape of the object to r _ _ _ _ _ the air resistance. r e d u c e The lines in wind tunnel tests show the pattern of a _ _ flow. The smoother the air flow, the l _ _ _ the air resistance. The shape with the least air resistance is the teardrop shape - this is the m _ _ _ streamlined. a i r l e s s m o s t

Beath High School - Int 1 Physics14 W _ _ _ tunnels are used to improve the streamlining of cars. Cars and Streamlining W i n d The shape of a car can be made like a teardrop or like an aeroplane wing to r _ _ _ _ _ air resistance. r e d u c e Sometimes a spoiler is fitted at the back to improve the air f _ _ _ making it more streamlined. f l o w Another way to reduce air resistance is to make the car closer to the g _ _ _ _ _. g r o u n d

Beath High School - Int 1 Physics15 When two forces are the same size as each other and act on the same object but in directions, they balance each other. The forces are called balanced forces. Balanced Forces Some examples of balanced forces are; opposite

Beath High School - Int 1 Physics16 Balanced Forces Some examples of balanced forces are; All of the objects shown above are acted on by b _ _ _ _ _ _ _ forces. b a l a n c e d

Beath High School - Int 1 Physics17 Examples of balanced forces When two tug-of-war teams are pulling against each other but neither is making any progress, the f _ _ _ _ _ applied by each team must be balanced. f o r c e s

Beath High School - Int 1 Physics18 Examples of balanced forces Before skydivers open their parachute they fall with a constant speed called their t _ _ _ _ _ _ _ velocity. This is because their weight is balanced by the a _ _ r _ _ _ _ _ _ _ _ _ on their body. t e r m i n a l a i r r e s i s t a n c e

Beath High School - Int 1 Physics19 Examples of balanced forces When they open their parachute they still fall at a constant speed but much slower than before because the air resistance is g _ _ _ _ _ _ with the parachute open. The air resistance is still e _ _ _ _ to the weight so the forces are still balanced. e q u a l g r e a t e r

Beath High School - Int 1 Physics20 Examples of balanced forces When a plane is travelling forwards, the air rushing over the wings creates an u _ _ _ _ _ force. u p w a r d When the plane is flying level, this upward force balances the w _ _ _ _ _ of the plane. w e i g h t When the plane is taking off and landing, the upward and downward forces are n _ _ balanced. n o t

Beath High School - Int 1 Physics21 Intermediate 1 Physics Movement Speed and acceleration

Beath High School - Int 1 Physics22 We can measure the average speed of any object by measuring the d _ _ _ _ _ _ _ it travels and the t _ _ _ it takes to travel that distance. Measuring average speed d i s t a n c e t i m e Average speeds are usually measured over l _ _ _ _ distances or l _ _ _ times. l a r g e l o n g

Beath High School - Int 1 Physics23 The average speed can then be found using the following equation: Measuring average speed Average speed = distance time metres (m) seconds (s) metres per second (m/s)

Beath High School - Int 1 Physics24 The distance can be measured using a tape or m _ _ _ _ stick. Measuring average speed m e t r e Time is measured by a s _ _ _ _ _ _ _ _ or sometimes by a timer which starts and stops automatically. s t o p w a t c h

Beath High School - Int 1 Physics25 Automatic timers are often operated by light g _ _ _ _. Measuring average speed g a t e s When a moving object cuts the beam of light gate 1, the timer s _ _ _ _ _ timing. s t a r t s When the moving object cuts the beam of light gate 2, the timer s _ _ _ _ timing. s t o p s In this case, the average speed = distance between gates time on timer

Beath High School - Int 1 Physics26 1.A car travels a distance of 45 m in 30 s. Calculate its average speed. Examples on calculating speed 45 Average speed = distance time = 30 = 1.5 m/s

Beath High School - Int 1 Physics27 2.A trolley passes through two light gates which are 2.5 metres apart. The timer measures a time of 15 seconds. What is the average speed of the trolley? Examples on calculating speed 2.5 Average speed = distance time = 15 = m/s

Beath High School - Int 1 Physics28 3.A trolley passes through two light gates which are 1.2 metres apart. The timer measures a time of 0.8 seconds. What is the average speed of the trolley? Examples on calculating speed 1.2 Average speed = distance time = 0.8 = 1.5 m/s

Beath High School - Int 1 Physics29 Your speed at any particular point during a journey is called the instantaneous speed - the speed at an instant. Instantaneous Speed Calculating this speed is the same as calculating the average speed but the time interval must be very s _ _ _ _. s m a l l

Beath High School - Int 1 Physics30 Measuring Instantaneous Speed Because the time to be measured is so small, there is a problem with r _ _ _ _ _ _ _ time (the time taken by a person to start and stop a timer). r e a c t i o n To measure the speed of a moving trolley, it is better to use a l _ _ _ _ g _ _ _ because there is no reaction time. l i g h t g a t e The trolley is fitted with a card. The timer measures the t _ _ _ the card cuts off the beam of light. t i m e

Beath High School - Int 1 Physics31 Measuring Instantaneous Speed It s _ _ _ _ _ when the card cuts the light gate beam and it stops again when the beam is remade. s t a r t s

Beath High School - Int 1 Physics32 Measuring Instantaneous Speed The instantaneous speed is calculated using the length of card as the d _ _ _ _ _ _ _ and the timer reading as the time, i.e. d i s t a n c e Instantaneous speed = length of card time on timer metres (m) seconds (s) metres per second (m/s)

Beath High School - Int 1 Physics33 Example on instantaneous speed A trolley is fitted with a card 0.10 m in length. The trolley is set in motion and the card cuts a light gate. The time on the timer is seconds. Calculate the speed of the trolley when it passes the light gate. = 4.0 m/s Instantaneous speed = length of card time on timer =

Beath High School - Int 1 Physics34 Acceleration is the change of speed of an object in one s _ _ _ _ _. Acceleration s e c o n d If an object is getting f _ _ _ _ _, it is accelerating – the speed of the object is increasing. f a s t e r If an object is getting s _ _ _ _ _, it is decelerating – the speed of the object is decreasing. s l o w e r Do not confuse acceleration with speed. A car can be travelling at a h _ _ _ speed but have zero acceleration; h i g h also a car can have a high acceleration but be travelling at a low s _ _ _ _ s p e e d (though its speed will not stay low for long!).

Beath High School - Int 1 Physics35 Car manufacturers often state a value for their car's acceleration to indicate its performance. Car performance The usual performance figure quoted is the t _ _ _ in seconds it takes for the car to increase its speed from rest to 60 mph. t i m e The smaller the time, the h _ _ _ _ _ the acceleration and the higher the performance. h i g h e r A high performance car might be quoted as: 0-60 mph in 5.0 s

Beath High School - Int 1 Physics36 The table below shows performance figures for some makes of car. Car performance Questions: a.Which car has the greatest acceleration? Explain your answer. b.Which car has the smallest acceleration? Explain your answer.

Beath High School - Int 1 Physics37 The table below shows performance figures for some makes of car. Car performance Answers: a.The car with the greatest acceleration is the Jaguar because it has the shortest time to make the same increase in speed as all the others.

Beath High School - Int 1 Physics38 The table below shows performance figures for some makes of car. Car performance b.The car with the smallest acceleration is the Mini because it has the longest time to make the same increase in speed as all the others. Answers:

Beath High School - Int 1 Physics39 Intermediate 1 Physics Movement Moving Bodies

Beath High School - Int 1 Physics40 When an object has its speed c _ _ _ _ _ _ by another object, we say the two objects collide. Collisions c h a n g e d MOVING BODIES Suppose object A is moving and collides with object B. The effect of the collision is to change the speeds of b _ _ _ the colliding objects. b o t h The change in speed of the colliding objects is greater when: a) the objects are moving f _ _ _ _ _ before collision b) the objects have a larger m _ _ _. f a s t e r m a s s

Beath High School - Int 1 Physics41 When an object has its speed changed, we say it has been acted on by a f _ _ _ _. Change in speed f o r c e (Forces occur during collisions). The larger the force the g _ _ _ _ _ _ the change in the speed. g r e a t e r The longer the time a force is applied the greater is the c _ _ _ _ _ of speed. c h a n g e

Beath High School - Int 1 Physics42 When an object is thrown or fired, it travels a distance horizontally before hitting the ground. The range of a ball Eventually even the fastest thrown or fired object hits the ground due to the force of g _ _ _ _ _ _ pulling it down. g r a v i t y This horizontal distance travelled is called the r _ _ _ _, r a n g e i.e.

Beath High School - Int 1 Physics43 The range of a ball thrown or hit is changed by: The range of a ball a) the s _ _ _ _ the ball is thrown or hit s p e e d (the f _ _ _ _ _ the speed the greater the range) f a s t e r b) the a _ _ _ _ at which the ball is thrown or hit. a n g l e

Beath High School - Int 1 Physics44 The range of a ball The distance (r _ _ _ _ ) a golf ball travels depends on the speed of the club and the loft (a _ _ _ _ ) of the club. The driver is designed to give the greatest speed at the best angle for maximum d _ _ _ _ _ _ _. r a n g e a n g l e d i s t a n c e

Beath High School - Int 1 Physics45 Whenever a ball bounces, it l _ _ _ _ some of its energy so it never reaches the same h _ _ _ _ _ again. Height of rebound l o s e s h e i g h t A ball dropped from a height of 80 cm might rebound to height of 50 cm. It will never rebound to a height of 80 cm. When a ball hits a surface, it will rebound to a greater height if: a) its speed on impact is l _ _ _ _ b) the surface it hits is h _ _ _. l a r g e h a r d

Beath High School - Int 1 Physics46 Intermediate 1 Physics Movement End of Unit