Physics Bridge Course

A magician pulls a tablecloth out from under dishes and glasses on a table without disturbing them. Which law explains this?

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

• None of these

Momentum is related to Newton's first law.

• True

• False

What will happen to a penny and a feather dropped from the same height in the absence of air?

• They will fall at different rates.

• They will not have momentum.

• They will float

• They will fall at the same rate.

Force exerted on a body changes it's

• Direction of motion

• Momentum

• Kinetic energy

• All of these

An object of mass 2 kg is sliding with a constant velocity of 4 m/s on a friction less horizontal table. The force required to keep the object moving with the same velocity is:

• 2 N

• 32 N

• 0 N

• 56 N

Newton’s third law of motion explains the two forces namely ‘action’ and ‘reaction’ coming into action when the two bodies are in contact with each other. These two forces:

• Have same magnitude and direction

• Acts on either body at normal to each other

• Always act on the same body

• Always act on the different bodies in opposite directions

A water tank filled upto 2/3 of its height is moving with a uniform speed. On sudden application of the brake, the water in the tank would

• Move backward

• Move forward

• Come to the rest

• Be unaffected

When the velocity triples, the kinetic energy increases by ______ times.

• 9

• 3

• 1.5

• 16

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 minutes?

• 15 J

• 0 J

• 25 J

• 82 J

In which situation is work not done?

• lifting a 20 pound box off the floor

• holding a 20 pound box above the floor

• sliding a 20 pound box across the floor

• sliding a 20 pound box up an inclined plane