REMIDI - ASAT Fisika Kelas 7

Which of these sets of forces are all non-contact forces?

• Friction, magnetic force, gravity force

• Magnetic force, gravity force, electrostatic force

• Gravity force, magnetic force, muscle force

• Electrostatic force, engine force, gravity force

A force can..... (i) Move a stationary object (ii) Change the direction in which an object is moving (iii) Increase the speed of a moving object (iv) Stop a moving object

• i,ii, iii

• i, ii, iv

• i, iii, iv

• all of it

An astronaut in an orbiting spacecraft experiences a force due to gravity. This force is less than when she is on the Earth’s surface. Compared with being on the Earth’s surface, how do her mass and her weight change when she goes into orbit?

• Mass decrease, weight decrease

• Mass decrease, weight unchanged

• Mass unchanged, weight decrease

• Mass unchanged, weight unchanged

A girl has a weight of 88 N on the moon, where g = 1,6 m/s². What is her mass?

• 55 kg

• 55 N

• 88 kg

• 8,8 kg

The units for Impulse are

• N/s

• N.s

• N

• m/s

The purpose of air bags on a car is to

• decrease time of impact.

• increase force of impact.

• increase the time of impact.

• decrease the impulse during impact.

A 2 kg cart has a momentum of 16 kg m/s. What is its velocity?

• 8 m/s

• 32 m/s

• 0.125 m/s

• 18 m/s

A 50 kg ball rolls down the street at 5 m/s. Calculate the momentum of the ball.

• 55 kg.m/s

• 100 kg.m/s

• 250 kg.m/s

• 500 kg.m/s

A 5 N force is applied to a 3 kg ball to slow it down from 9 m/s to 3 m/s. What is the impulse on the ball?

• -18 N.s

• -45 N.s

• -10 N.s

• -2.5 N.s

Mana yang memiliki momentum lebih besar?

• Seekor burung kolibri terbang di jalan (v = 1 m/s)

• Sebuah bus berhenti di lampu lalu lintas

• Seekor burung kolibri melayang di pengumpan

• Sebuah bus melaju di jalan (v = 10 m/s)