Laws of Motion

Which of the following explains why a passenger in a speeding bus is thrown forward when the bus suddenly stops?

• acceleration

• gravitation

• inertia

• interaction

The action and reaction forces referred to in Newton's third law of motion ____________________________.

• act on different bodies

• act on the same bodies

• need not to be equal in magnitude

• must have the same line of action

The amount of force needed to give a 1 kg object an acceleration of 1 m/s² is one ____________.

• dyne

• erg

• joule

• newton

A mass is doubled and the net force is kept constant. The acceleration of the body _________________.

• is halved

• remains the same

• is doubled

• is tripled

A bag lies on top of a table. Which statement correctly describes the situation?

• The bag exerts no force on the table.

• There are no forces acting on the bag.

• The bag is absolutely at rest in any reference frame.

• There are may forces acting on the bag but they balance each other.

pushing a chair: contact force;

falling fruits:__________________

• centripetal force

• electrical force

• magnetic force

• noncontact force

mass: inertia;

weight: _____________________

• centripetal force

• electrical force

• gravitational force

• magnetic force

propulsion of rockets: law of interaction;

accelerating car: _________________________

• law of inertia

• law of acceleration

• law of universal gravitation

• law of conservation of energy

acceleration and force: direct proportion;

acceleration and mass: _______________________

• direct proportion

• direct square proportion

• inverse proportion

• inverse square proportion

newton: force;

kilogram: ____________________

• acceleration

• mass

• speed

• weight