Pushes and Pulls
What do you call a forces that moves and object away from you or toward you?
Push or Pull
The forces the pulls objects down to Earth's surface
Gravity
What happens to an object’s motion when you apply a greater force to it, assuming mass is the same?
the object’s change in motion (acceleration) increases — it speeds up more.
What does it mean when forces on an object are balanced?
forces cancel so there is no change in motion.
Give one everyday example of a push and one example of a pull
Answers will vary
two identical toy cars are pushed with the same force; one speeds up more than the other because one has less friction. Which idea from the standards does this relate to?
The greater the force applied, the greater the change in motion; friction affects net force and resulting motion.
A box sits on the floor and does not move. Name the two main forces acting on it and explain how they balance
Gravity (weight) pulling down and the floor’s normal force pushing up; they are equal in size and opposite, so net force is zero.
Describe how a push or pull can change an object’s speed or direction.
A push or pull applies force; if force is in same direction as motion it speeds up; opposite direction it slows down; if at an angle it can change direction
A ball is thrown straight up. At the top of its path, what is happening to its motion and why?
At the top, the ball’s upward velocity is zero for an instant; gravity is pulling it downward, so it will start falling back.
If you apply the same force to a tennis ball and to a bowling ball, which one will change its motion more?
The tennis ball will change motion more because it has less mass; the same force causes a larger acceleration for smaller mass.
Describe a situation where a moving object slows down because of an opposing force. Name the opposing force
A rolling ball slows due to friction; friction is the opposing force that reduces motion
Skateboarder slowing down on grass, friction
Sarah uses a broom to move dust across the floor. Is the broom applying a push or a pull?
Push. The broom applies force against the dust to move it away, causing motion across the floor.
A small toy car (mass = 0.5 kg) and a larger toy truck (mass = 2.0 kg) are both pushed with the same force. Describe which will accelerate more and why
The toy car (smaller mass) will accelerate more because for the same force, objects with less mass have greater change in motion.
Explain why pushing on a heavy stone with a small stick might not move the stone, using the idea of opposing forces and balance.
the push force is too small compared to friction and the stone’s inertia (its large mass); opposing forces and the stone’s large resistance result in balanced forces, so it doesn’t move.
Two students push a box from opposite sides with equal strength and it does not move. What does this tell you about the forces acting on the box?
The forces are balanced (net force = zero), so there is no change in motion
Describe an investigation we could do to test that increasing the force on an object increases its change in motion.
Example: Applying different force on toy car (different height ramps) measuring the distance
wo tug-of-war teams pull with equal force and the rope stays in the middle. Explain, using balanced/unbalanced force vocabulary, why neither side wins.
The forces are balanced (net force = 0), so there is no acceleration or movement toward either side.