AnswersDISD CR Physics 2020-2021Newton's Second Law

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The free-body diagrams of four objects are shown.

Question illustration
A
W
B
X
C
Y
D
Z
3
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A sports car and a minivan run out of gas and are pushed to the side of the road. Which is easier to push, and why?

A
the minivan, because it has more mass and therefore more inertia
B
the minivan, because it has less mass and therefore less inertia
C
the sports car, because it has more mass and therefore more inertia
D
the sports car, because it has less mass and therefore less inertia
4

According to Newton’s first law of motion, what will an object in motion do when no external force acts on it?

A
come to a stop
B
move at the same velocity
C
speed up
D
change direction
5

Juan draws a free-body diagram of an object that is in dynamic equilibrium moving to the left.

Question illustration
A
X: 45 NY: –45 N
B
X: –45 NY: 30 N
C
X: 30 NY: –45 N
D
X: 30 NY: –30 N
6

What is the mass of a crate if a net force of 12 N gives the crate an acceleration of 0.20 m/s2?

A
2.4 kg
B
6 kg
C
12.2 kg
D
60 kg
7

A ball is falling at terminal velocity. Terminal velocity occurs when the ball is in equilibrium and the forces are balanced.Which free body diagram shows the ball falling at terminal velocity?

A
Option
B
✓ Correct
C
Option
D
Option
8

Which situation is contrary to Newton’s first law of motion?

A
An object at rest begins to move when an external force is applied.
B
A moving object has a constant velocity under the influence of balanced forces.
C
An object at rest stays at rest as long as unbalanced forces act on it.
D
A moving object slows down when an external force is applied.
9

A baseball has a mass of 145 g. A bat exerts a force of 18,400 N on the ball. What is the acceleration of the ball?

A
1.27 x 102 m/s2
B
2.67 x 103 m/s2
C
1.27 x 105 m/s2
D
2.67 x 106 m/s2
10

A box is being pulled to the right. What is the direction of the gravitational force?

A
up
B
down
C
right
D
left
11

Juanita studies several free-body diagrams in which a normal force is shown. What is always true about a normal force in a free-body diagram?

A
It is opposite the weight.
B
It is perpendicular to a surface.
C
It is opposite the net force.
D
It is parallel to a surface.
12

The gravitational force between two objects is 3600 N. What will be the gravitational force between the objects if the mass of each object is reduced to one-third of its original mass?

A
400 N
B
1200 N
C
10,800 N
D
32,400 N
13

In the equation for the gravitational force between two objects, which quantity must be squared?

A
m1
B
m2
C
G
D
d
14

Shari uses the data in the table to predict how her weight on Venus would compare with her weight on Earth.Which is the best prediction Shari could make?

Question illustration
A
Her weight is greater on Venus because Venus has less mass.
B
Her weight is lower on Venus because the acceleration due to gravity is lower.
C
Her weight is lower on Earth because it is farther from the Sun.
D
Her weight is greater on Venus because Venus has a smaller diameter.
15

Which formula is used to calculate the mass of an object if the force and acceleration are known?

A
m = Fa
B
m =
Option B
C
m =
Option C
D
m = F – a
16

Review the table detailing the mass of Jupiter’s moons and their distance from the planet.

Question illustration
A
Io
B
Europa
C
Ganymede
D
Callisto
17

The mass of Mars is 6.42 × 1023 kg. Its moon Phobos is 9378 kilometers away from Mars and has a mass of 1.06 × 1016 kg.

A
5.16 × 1015 N
B
5.16 × 1021 N
C
4.84 × 1022 N
D
4.84 × 1025 N
18

Kamala puts on inline skates and stands facing a wall. When she pushes against the wall, she rolls backward.Why does pushing harder make her roll faster?

A
The force of friction between the wheels and the ground decreases.
B
The force of the wall pushing on her increases.
C
The additional force decreases her weight.
D
The extra force causes an increase of the normal force from the ground.
19

How much force is needed to accelerate an object of mass 90 kg at a rate of 1.2 m/s2?

A
0.013 N
B
75 N
C
108 N
D
1080 N
20

What is the purpose of a free body diagram?

A
to show the velocity of an object
B
to show the acceleration of an object
C
to show the forces acting on an object
D
to show the direction of motion vectors of an object
21

20455075

A
20
B
45
C
50
D
75

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