Linda L. Smith NASA Astrophysics Educator Ambassador

Look at the poster and identify examples of Newton’s 1 st law of motion and explain.

Figure Skater To begin moving, A figure skater must apply a force using her skates. Once in motion, She’ll continue to glide along the ice in a straight line for a long time Unless she applies another force.

Tug of War When each end of a rope is pulled, the rope will move in the direction of whoever is pulling harder whoever is applying more force. In this case, the magnitude or strength of A (on the right) is greater than that of B (on the left), so the rope accelerates to the right.

Snowboarder A snowboarder experiences a force due to gravity which pulls her down. She will move in a straight line unless she applies a force to the board, changing direction.

Train A train is a very massive object, and therefore has a lot of inertia. Once in motion, it is very difficult to stop, requiring a very large force to slow it.

Jogger A jogger experiences many forces while running: Gravity The push of her feet, Friction of her shoes on the ground, Air resistance. Her legs, together with the friction of her shoes, overcomes her inertia to propel her forward.

Car Hitting a Wall A car rolling down a hill is being moved by the force of gravity. When the car hits the wall, the greater inertia of the wall stops it. But anything not attached to the car will still move forward, So the man running after the car will lose his coffee, his lunch, and his briefcase.

Look at the poster and identify examples of Newton’s 2 nd law of motion and explain.

Waterfall As the water flows over the edge of the rocks, gravity, which exerts a downward force on it, causes it to accelerate downward: The water moves faster the longer it falls

Throwing a Ball When the girl throws the ball, she is applying a force to it and accelerating it. As soon as she lets go, gravity, which also applies a force, accelerates the ball downward.

Cube being Pulled A heavy cube sits on a surface. If someone applies a force to it that is stronger than the effect of gravity and the frictional forces on it, Then the object will accelerate.

Swinging When a girl swings, gravity accelerates her downward from the top of her arc. Her inertia keeps her moving at the bottom, and the force of the tension in the ropes makes her move in an arc upwards. Gravity then pulls her down, decelerating her until she stops, and the motion repeats.

Swivel Chairs The velocity of an object includes its speed and its direction. Acceleration is the change in velocity, So changing the speed and/or the direction of an object is an acceleration. In a swivel chair, the woman feels an acceleration because her direction is constantly changing as she spins.

Baseball Player A baseball player applies a large force to a baseball, accelerating it to high velocity. If the ball had more mass, that same force would not accelerate the ball to such a high velocity.

Cars When a driver hits the gas, the wheels apply a force on the ground due to friction. This force accelerates the car forward. The brakes apply a force to the wheels, which in turn apply a frictional force to the ground, decelerating the car.

Look at the poster and identify examples of Newton’s 3 rd law of motion and explain.

Rocket A rocket works by propelling mass out the back end at high velocity. The action of the mass of the burning fuel accelerating out the back end applies an opposite reaction force to the rocket, moving it forward. The rocket is not simply pushing against the ground. This works even in the vacuum of space

Trucker and Ramp When the man pushes the heavy box up the ramp, he applies a force to the box. The box reacts by pushing back. If the man pushes hard enough, he can overcome gravity and friction, accelerating the box up the ramp.

Shopper The woman pushing a shopping cart feels an opposite force applied by the cart on her.

Baseball Player When the baseball player hits the ball with her bat, the ball reacts by pushing back on her. The player feels this as a jerk back-wards when the bat contacts the ball.

Fish Fish propel themselves forward by push-in water back, behind them. The water reacts by pushing the fish in the opposite direction, forward.

Hand Pulling On Rope Connected to a Weight When the hand pulls the rope attached to the weight, it applies a force to the weight, The weight reacts by applying a force in the opposite direction. The hand feels a resistance.

Bridge Suspension bridges are all about actions and reactions. The roadway hangs from the vertical cables, pulling them down, and the vertical cables react by holding the roadway up.

Soccer Player When the boy runs up to the ball and kicks it, he applies a force to the ball, moving it forward. The ball reacts by pushing back against the boy, which he feels as pressure on his foot when he kicks the ball.

Hammer and Nail The hammer hitting the nail applies a large force to it. The nail reacts by push-in back against the hammer. The carpenter feels this as a jolt backwards against his hand.

Look at the poster and identify examples of Newton’s law of gravitation and explain.

Solar System All the planets in the solar system orbit the Sun due to its gravity. The inner planets are closer to the Sun and feel more gravity, so as a result they move faster.

Astronaut An astronaut in orbit is accelerated by Earth’s gravity. But without the balancing upward force from the ground, she falls freely.

Sir Isaac Newton Isaac Newton was the person who realized that all massive objects in the Universe apply the force of gravity to all other massive objects. An apple didn’t really fall on his head, but he did realize that the force causing an apple to fall is the same as the force causing the Moon to orbit the Earth – The Earth’s gravity.

Cyclist falling or girl falling Bicyclists speeding down a hill and falling towards the ground are aware of gravity. The gravitational pull from the Earth is what makes the cyclist accelerate towards the ground.

Swift Satellite The effect of Swift’s horizontal velocity (from its launch rocket) exactly cancels the downward velocity gained from the acceleration due to Earth’s gravity. This gives Swift its circular path around the Earth just as the moon orbits the Earth.